Combat Rules

This page contains (the majority of) the combat-related House Rules that we use in our Rifts campaigns. My main focus here is on making combat move a bit faster. Outside of that, we're largely doing things rules-as-written ("RAW"), with extended clarifications detailed below.

Combat Rule Zero: How to Not Die in Combat

Rifts is a deadly setting. This is especially so for squishy "SDC" characters when dealing with tougher "MD" enemies and weapons. Even if you're wearing MDC armor, many attacks cause pass-through damage, so it's not a good idea to rely entirely on nothing more than a good shell.
The most important rule of surviving this kind of deadly combat is a simple one: Don't get shot. This is easier than you may think. The simplest ways to ensure this happens are to keep these in mind when considering combat:

Don't start fights unless you know you can win.

If you only think you can win, think harder until you know you can win. Otherwise, don't start the fight.

Set up and make use of as many battlefield advantages as possible.

Take cover behind the toughest thing available. Sometimes this is nothing more than another PC with a robot.

Aim your shots for maximum damage - in other words, kill them first, before they can kill you.

If you don't think you can survive, run away and live to fight another day.

If you're trapped and you can't win, surrender. It might just save your life.

Structure and Flow

(June 2021 update) Inspired by a discussion thread on the Rifts reddit, we're using a "Rounds, Passes, and Turns" approach to initiative.

Rounds, Passes, and Turns

Combat consists of a series of 15-second melee rounds (also commonly referred to as melees), which are broken into three 5-second passes, which in turn are further broken into a sequential series of turns.

Actions

On your Turn you can take one or more actions (aka "attacks"). These are detailed further below.

Initiating Combat

When a new combat encounter begins, first resolve surprise actions, then roll the initiative for the first round of the fight.

Surprise

Some in-game situations may result in one side completely surprising the other. This usually requires a major pre-planned and well-coordinated effort, and almost certainly requires that the victims be completely unaware of the presence of the attackers. There are several Ambush-related skills that can come into play here on both sides.
When this is deemed appropriate, the surpriing party gets a free no-roll-required single-phase (see below) initiative round of action at the beginning of combat. Characters in the surprising party get the actions they would be allowed in the first phase of a combat round. Opponents who are aware of attacks can attempt to defend, but the Surprised combatants do not get to "Take the Initiative" during this round.
On the following round, roll initiative as normal.

Rolling Initiative

Initiative is rolled more or less as detailed in the core rules, using a d20. Initiative modifiers are actually pretty rare - most characters probably don't have any, so if you do, you'll likely know it already.
During the three passes of a combat round, the players cycle their turns in the initiative order they rolled for that turn as normal. At the end of the first and second passes of a round, start again from the top for a new pass. At the end of the third pass of a combat round, after everyone has finished their turns, if there is still fighting happening then it's time to start a new combat. Reroll initiative for the new round, then proceed through the passes with the new turn order.

NPC Initiative is Pre-Set!

For the sake of minimizing the GM's many, many, many dice rolls, NPCs all have pre-set initiative scores of 10 plus their initiative mods. The GM will let the PCs know these status numbers after the first round has passed. Only the PCs require a re-roll between rounds.

"Having the Initiative"

Palladium games are somewhat dodgy on the term "having the initiative," mainly in that it doesn't actually seem to really mean anything tangible. So let's clarify.
First off, ignore the glossary description of Initiative on p. 345 of the RUE.
Instead, think of it like this: If it is your turn in the round - as in the turn matching the Initiative result that you rolled - then you "Have the Initiative" in the current moment. As in "it is your initiative" now, and you can do any of the actions you could do on your initiative.
When you "Have the Initiative," you can choose to use your available APMs to take Actions. You can spend all of them making attacks on your initiative, or split them between attacks and supplementary actions, or even save some to defend against later attacks on you (if you don't have Automatic Parry or Automatic Dodge, for example).

"Losing initiative" Effects

Some effects of actions may cause a target to "lose initiative." For the sake of simplicity, this means they now act last this turn. Here's how this works:

If they have not yet acted in any pass this round, their Initiative roll is set to Zero in the current initiative order.

If they have already acted this round, then on the next round they do not get to roll Initiative, and are instead given an Initiative score of Zero.

Multiple such effects do not stack. If you have Lost the Initiative, additional such effects are ignored - you cannot make someone Lose something they have already lost.

Taking Action

Actively participating in combat requires taking "actions." Each character has a number of "Attacks per Melee" (aka "APMs") granted by their OCC, skills, and a few other sources. These should already be noted on your character sheet.

Sources of APMs

Your APMs come mainly from your Hand-to-Hand (H2H) Combat skill. There are many other sources of additional Attacks/Actions in Rifts, which I am attempting to more specifically clarify in these rules. As I find them, I will add them to the growing list of clarifications below. Until ruled otherwise, these clarifications supersede all conflicting rules from other materials:
Attack Actions Sources Clarifications

Boxing Skill: Adds one additional Attack action that can only be spent to Punch someone. It can be spent as one of the actions required for multi-action-cost attacks as well, such as a standard Power Punch.

Hand-to-Hand Skill: No more than one-half (rounded up) of your H2H-provided Attack actions can be spent on standard ranged attack actions with weapons that use Modern WP Skills. Any additional ranged modern attacks from this Pool are all made Wild.

Magic/Psionics: Additional attacks granted by magical or psionic enhancement usually can be spent on any Action, unless the source material is more specific in its scope.

OCC/RCC: Any additional attacks from OCC/RCC abilities must be judged by the nature of their bonus. General attack additions (such as the bonus attack a Psi-Stalker gets) can be used on any Actions. Others may or may not have particular limitations.

Robots & Power Armor (aka RPAs): (includes related combat skils) Additional attacks from RPAs and their combat skills can only be spent on actions that directly involve the use of the RPA and/or any of its linked or attached weapons.

Vehicles: Similar to RPAs, but for Vehicles and their extended gear.

To keep track of this, make a note of your combined total Actions from all sources at any one time. So if you have 4 from H2h, 1 from Boxing, and 1 general attack from your RCC, write down 6. Then note how many can/must/not be spent on what. Continuing the above example, at most 3 can be spent on modern ranged, and 1 must only be spent on Punching.

Actions in Combat Passes

When it's your turn, you must choose how to act. Your APMs are synonymous with "actions" in Palladium, providing the core currency of action in any single round.
In these house rules, your APMs are split evenly across the three passes of a round. Divide your actions across them, and if the division is uneven then assign the remainder across the first two rounds. For example, Joe Schmoe with 4 APMs assigns his actions in order as 2/1/1, while Jill la'Killz with 5 APMs spreads them out as 2/2/1, and Benny BoomBoom with 8 APMs gets a spread of 3/3/2.

Spending Actions

When you Have the Initiative, you can spend an Action to do any of the following (within the limits of the Action's source, as detailed immediately above):

Attempt an attack action (default cost is 1 APM).

Activate psionic abilities with an increasing Action cost: the first costs 1 APM, the second costs 2, the third costs 3, and so on.

Cast spells with action costs based on the spell levels. See Magic Rules for specific costs.

Add attack effects that normally cost Attacks (aiming, called shots, etc)

Perform other miscellaneous non-attack actions (reloading, etc - see further below)

Outside of your Initiative you can spend Actions to:

Attempt to Parry an incoming attack (if you don't have Automatic Parry)

Attempt to Dodge an incoming attack (if you don't have Automatic Dodge)

Any in-the-books actions or effects that require a specified number of Attacks/Actions in order to perform keep their normal costs.

Unspent Actions do not Carry Forward

Your action pool is re-set at the start of each of your turns. Any APMs available to you in a pass can be spent to start actions, or held to defend between passes, but they vanish when your next turn begins. If you need to spend more APMs than you currently have, see Long Actions, below.

Gaining and Losing Actions

Any effect that gives you an APM adds to the current pass if it happens on your turn, otherwise it is added to your next turn.
Any effect that makes you "lose" an action, or otherwise unexpectedly increases an action's cost, must first be spent from your current pool. If you have no current APMs available, the costs come from your next pass(es).

Types of Actions

Attacking Actions

Attacking is complex enough that it has is own full section, further below.

Defending Actions

Defense actions like Parry, Dodge, and Roll are performed after the triggering attack roll is fully calculated and declared aloud. If the rules state that they cost you one or more of your APMs in order to activate, spend them first from your current pool of available APMs. Once that pool is depleted, you can still keep defending, but you begin spending APMs from your future passes, depleting them in order. There is no limit to this (outside of reason and common sense), thus it is technically possible to end up with a whole lot of action-less combat rounds in your near future following a single round of heavy defending.

Interrupting Actions

Sometimes you may have an option to "interrupt" another character's action. In this case, you both must roll Speed checks (1d100 + SPD score). If your roll is higher, then you successfully get to perform your action before your opponent's. You Have the Initiative, and then the other combatant takes it immediately after your action is resolved. If their roll equals or exceeds yours, then it is vice-versa. Normal Initiative rules then resume.

Countering Actions

Some actions may specifically give you a "counter" or "riposte" effect, applied to or in response to another character's action. When this happens, you take the initiative immediately after the triggering action is resolved, and execute your counter-action. When done, initiative returns to normal.

Simultaneous Actions

Some actions allow you to take an action simultaneous to aother character's action. When this happens, you both execute and fully resolve your respective actions, and then apply their respective effects simultaneously. Neither action leads, follows, counters, interrupts, or prevents the other. In other words, resolve each action as if the other never happened.

Long/Multi-APM Actions

Sometimes you may wish to perform an action that costs more APMs than you have available in the current initiative pass. These actions take an extended amount of time to complete, starting in te current pass (spending all available APMs) and completing in the next one (spending the remaining APM cost once it becomes available). In such cases, you don't just "bank" the APMs for later - you must actually start performing the action, and keep at it across consecutive passes. This may or may not be obvious to anyone watching, at the GM's call.
For example, let's say it's the first pass of a round, you've got 4 APMs (split as 2/1/1), and on your first action you want to take an aimed+called shot at an opponent. That normally costs 3 APMs total, but you've only got 2 this pass. So you get into position, spending the first 2 APMs immediately to line up the shot, then on your next turn you spend the remaining 1 APM and execute the attack.
This cost can carry across multiple passes, and even multiple rounds. For example if you only have 4 APMs but you want to do something that costs 5, then you must begin the action on your first turn of the current round, and then execute it at the start of your first turn in the next round.
Long actions may be interrupted per those rules above. It's the GM's call whether or not an interrupting action literally interrupts the long action, preventing it from completing. If this happens, the long action is broken, and all APMs spent on it are wasted.

"Holding" Actions

If you choose to Hold your action until later in the pass or round, you must state a triggering condition. If that condition comes into play, you can immediately execute that action, provided you have enough APMs to spend on it. If doing so would interrupt or possibly supersede another combatant's action, this is considered Interrupting (see above).
You can Hold across rounds. If so, roll the next Initiative as normal. Your count of APMs resets as normal. Your Held Action continues to hold as described above until you next Have the Initiative.

Passing

If you choose to "pass" the initiative on your turn, you give up the option to take any further actions this pass beyond defending. Any APMs you had available this pass are lost at the start of your next turn. Note that if you are out of actions, you can only pass.

Free Actions (New)

Some actions are small enough to not warrant spending any APMs. These minor actions can be done between other actions, as long as they are reasonable. Specific clarifications below (list likely to grow through play):

Movement costs no actions, but note the movement-based action penalties already part of the rules as written.

Misc. Actions and their Costs

In addition to the above, there are a few miscellaneous actions that require spending a Combat Action. They will be added to the growing list as we find them:

???

Draw a weapon: Drawing a ready weapon costs an Action. Pulling a weapon from your bag costs two or more.

Reload a weapon: Costs 1 Action unless the weapon description says otherwise.

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Attack Actions

Combat Attacks are always a roll of 1d20 plus modifiers as detailed below. A natural 20 is a Critical Strike and does double damage. A natural 1 is not an automatic failure, however if the roll plus modifiers is a miss, then it is a Critical Failure, and something bad may happen (see the Critical Failures section, further below).
On a successful attack, the defender either attempts to roll a defense or takes damage. The location of the damage is chosen by the defender, unless the attacker performed a Called Shot and hit the required Called Shot target (usually a 12).
When rolling damage, you may need to multiple or divide the amount, depending on the weapon. See Damage Systems for more details.
Details for what you need to roll are shown on the table below. Also shown are the Action costs and the default hit locations for uncalled shots.

Attack Type	Roll	Mods	Actions	Hit Location
Melee	5	Attr+H2H+Sitch+WP+Weapon	1	Target Decides
Melee Called	12*	As Melee, possible GM?	2	Attacker Decides
Ranged	8	WP + Sitch + Weapon	1	Target Decides
Ranged Aimed	8	As Ranged, +2	2	Target Decides
Ranged Called	12*	As Ranged, possible GM?	2	Attacker Decides
Ranged Aim+Call	8	As Ranged Aimed+Called	3	Attacker Decides

* By default, called shots require a total roll of 12 or higher to hit. This varies based on the target. See the Called Shots rules further below.

Melee Attacks

Some clarifications on Melee Combat options.
Punching and Stabbing (aka Melee): In Melee combat, you get to add all your relevant bonuses from Attributes, H2H skill, and relevant WPs. You want your total Strike roll with modifiers to at least equal 5 or more. In other words, results of 1-4 are misses.
Specific Melee rules, sorted alphabetically:

Back Flip: This rule is stupid and I don't know why anyone would ever do it. Instead, just roll a normal attack or dodge and do that instead. Feel free to narrate it as a backflip if you like.

Bodyblock/Etc: Expanded rules further below.

Called Shots in Melee: In order to call a shot in Melee combat you must spend an additional APM when attacking. In order to then hit that target, your attack roll must meet the Called Shot target. Unless otherwise specified, this defaults to 12. If the target is not met, the victim choose the target instead.

Death Blow: If your H2H gives you this ability, it rocks. You do not have to "call" it in advance, but it does still take two actions. So if you make an attack, and score a death blow, you can then choose to spend another Action to activate it. Otherwise it follows the rules as written.

Disarm: If your H2H gives you this ability, you do have to declare you are using it, either when you Strike or Parry. If you use it as a Parry, you do not have to get a "natural" 19 or 20, instead only needing to roll high enough to defend the attack. Note: In either attack or defense, rolls to Disarm use only your Disarm bonuses, and not Strike or Parry (unless you are specifically using a disarming weapon, in which case go to town with your bad self).

Knockout Attacks, Etc: Similar to Death Blow in that they activate on certain natural rolls and do not require being called in advance. In order to activate them, you must spend an Action after the required results are rolled.

Breakthrough/Knockback/Bodyblock Actions

House rules for this, based on those from RUE but with some tweaked math. Normal melee attack roll, and defender can dodge as normal but not parry. Attacker states their intent, such as "knock that guy to the ground" or "push through that guy blocking my way." Attacker rolls percentile with a 50% base chance of success, modified by 2x the difference in PS. For example, if you are PS:13 and body checking someone of PS:23 (10 points difference), your chance of success is 30% (50 base minus 20). If characters are in different categories of strength, add a 20% modifier per category "step" along the track of: Normal -> Augmented -> Robotic -> Supernatural. For example, a Supe character slamming a Normal character would get a +60% bonus, while a Robotic character slamming a Supe character would have a -20% penalty.
Should the intent be to knock down, defenders trained in specific "Balance" skills can attempt to use them as a sort of "Save" if they are successfully slammed, in order to resist being bowled over completely. If successful, the defender is knocked _back_ but is not _down_.
If the attacker chooses, and the initial attack roll is successful, they can also do damage as a restrained punch. Defenders can Roll w/ Punch as normal.

Ranged Attacks

Some clarifications on Ranged Combat options.
Shootin' Bows: These are "ancient" weapons with ranged mods. Target for the roll is 8 or higher at short/medium range, and 13 or higher at long/extreme range, same as with guns. Bows receive strike bonuses from high PP, but with limits. Your attack bonus comes primarily from your WP Archery and Targeting skill. Strike bonuses from a high PP stat apply only up to the Strike bonus from the Archery skill. So if your PP Strike mod is +6 but your Archery strike mod is only +2, then you add at most +2 from the high PP, for a combined total of +4.
Shootin' Guns: When shooting guns, the only modifiers to your Strike rolls are those from your relevant WP, your chosen action (aim, wild, etc), and the gear itself (e.g. Wilk's brand laser guns often have +1 to Strike on aimed shots). DO NOT add in your bonus from H2H skills or high stats. Your target depends on the range. See below.
Shootin' Guns at Point Blank: When shooting a target that is within punching range, the target is the same as melee (5) and the target can attempt to parry your attack.
Shootin' Guns at Short to Medium Range: If your target is within half the maximum range of your gun, this applies. You want your total Strike roll with modifiers to at least equal 8 or more. In other words, results of 1-7 are misses.
Shootin' Guns at Long to Extreme Range: If your target is between half and full maximum range of your weapon, this applies. You want your total Strike roll with modifiers to at least equal 13 or more. In other words, results of 1-12 are misses.
Special Option: Covering/Pinning Fire (NEW): This action is only available to weapons that have a burst fire option. This lets you spray a targeted area with bullets/blasts in order to keep one or more opponents pinned down. To use this, dedicate one or more of your available Actions to Covering Fire, and mark off that many bursts of ammo. Then roll that many Burst attacks.
Anyone that starts in, ends in, or passed through the targeted area is automatically hit once for each of your committed APMs, unless they are under cover. Targets can attempt to dodge each hit separately, using normal dodge rules against your attack rolls. The damage for a hit is as a single shot from the weapon (and not full burst damage).
Activating Covering Fire ends your active turn immediately as if you have Passed this round, as you are now spraying down an area through to your next initiative. Parrying, Dodging, or Rolling before your next initiative ends the effects of Covering Fire.
Note that the size of a covered area is something we'll play by ear on a case by case basis. Consider the number of shots in your bursts and the speed of their flight.
Throwin' Grenades: These have their own rules defined a bit further below.
Throwin' Knives and Such: Throwing a weapon uses the same ranged targets as with guns and bows. The strike bonus is the combination of your PP strike bonus and your Thrown bonus from the relevant Ancient WP skill. Other attack bonuses do not apply unless they specifically say "thrown."

Common Ranged Attack Mods

The most common applicable ranged attack modifiers are listed on p. 361 of the RUE. Some expanded notes:

Aimed Shots: You can aim for a +2 bonus. This may not seem like much, but it's worth it for called shots and for tricky opponents.

Called Shots: The p. 361 table says "No bonuses" but it really means "No additional bonuses." The "no bonus" is misleading, as it is only meant to imply that the strike bonus from Aimed does not apply to Called Shots, unless you spend three total actions doing an "Aim Called Shot."

As with Melee, Ranged Called Shots require hitting a minimum total Strike roll in order to hit the called location. Unless specified otherwise, the default target is 12. Successful attacks that do not meet the target instead hit a location chosen by the victom.

Target is Behind Cover: There are often additional penalties based on how well-covered the target is, ranging from -2 to -10. For example, shooting a small target that is also behind cover is especially difficult.

Target is Moving: For my rules, this is also applied to attackers who are moving. See Movement described further above.

Size Differences in Ranged Combat (NEW)

Most "small target" modifiers in Rifts tend to assume the target is being attacked by someone of equal size, using weapons built for that scale. I'm adding a size difference system of modifiers, inspired by old 3rd ed D&D. Basically smaller targets are harder to hit by weapons designed for larger scales, and larger targets are easier to hit by weapons designed for smaller scales. This is based on eyeballing comparative size classes, considering both the combatants and the weapons they are using. When attacking something smaller than you, subtract the size class difference from your Strike roll. When attacking a larger target, add the difference to your roll instead. See below:

Size	Equivalent
0	An acorn
1	A common tree squirrel
2	A golden retriever
3	An adult human
4	A Toyota Corolla, smaller power armor
5	A Glitter Boy, larger power armor, most large ATVs
6	An AT-ST / CS Spider Skull Walker / Star fighter ship
7	An AT-AT / CS Death's Head Transport / Drop spaceship
8	A heavy freighter spaceship
9	A star cruiser
10	The Death Star
11	Yo momma

Defending (Parry/Dodge/Roll)

When you are attacked in combat, you can usually attempt to defend against that attack.
Defending (Dodge/Parry): Choosing to dodge or parry only requires spending an Action if you don't have the associated "Automatic" defense ability. Roll a d20 + mods and try to equal or exceed the attacker's total roll. Modifiers are as follows:

Situation	Modifier
Dodge Melee Attack	1d20 + Attr + H2H
Dodge Ranged attack	1d20 + Attr + H2H
Dodge Gunfire at =< 10 feet	As Ranged but -10
Dodge Gunfire at > 10 < 50 feet	As Ranged but -5
Parry Melee	1d20 + Attr + H2H
*Parry Energy at =< 10 feet	As Melee but -10
*Parry Energy at > 10 < 50 feet	As Melee but -5

*=Parrying Energy weapons requires very special circumstances
Parry Restrictions Clarification: By default, using Rules as Written, a combatant can parry incoming attacks from up to three opponents each round (or two, if using a certain Paired Weapons ability). The attacker(s) that you have chosen to parry is locked-in the first time you decide to Parry an incoming attack between turns, and resets each time your turn comes back around.
Rolling with Punch: Free if you have H2H basic or better, otherwise it costs an Action. Rolled on a d20 plus H2H mods. Equal or exceed the attacker's roll and you take half damage.

Grenade Attacks

Grenades have some special rules added to simulate battlefield action.
Grenade Targeting: Like all ranged combat attacks, the target for up to medium range is 8, and up to long range is 13. Strike mods are from a high PP and the Targeting skill only.
Grenade Delay: Thrown grenades explode at the end of the combat round in which they are thrown, on Initiative Zero.
Grenade Scatter: Thrown grenades use a scatter die (NPC has one) to determine how far away and in what direction they roll/scatter before detonating. A bullseye on the scatter die, or a nat 20, indicates a direct hit (no scatter). Different-sized grenades have different amounts of potential scatter:

Size/Type	Scatter
Rifle/Launch	1d6 yards
Hand	1d4 yards
IED Thrown	1d8 yards

Missile Attacks

I've revised missile combat rules heavily. See further below.
Strike Rolls: The core bonus to firing missiles is changed to this: You get a +1 to strike for each missile in the volley. Use the same target numbers as per Shootin' Guns. Boom. Simple. Yes that means an automatic +1 to strike on all single-missile attacks. The target for the Strike roll is determined per standard ranged attack rules (i.e. base of 8, plus situational mods).
Damage: Every missile attack has a base Damage Multiple equal to the number of missiles in the volley (this is important for defensive counter-volleys, detailed further below). Multiply the base missile's damage roll by the number of missiles in the volley. So two missiles is x2 damage, five missiles is x5, and so on.
Blast Radius in Volleys is increased by 100% per every doubling of the number of missiles. For example, take a single missile with a blast radius of 20 ft. In a two-missile volley, that increases to 40 ft. At 4 missiles it increases to 60 ft. At 8 missiles it increases to 80 ft. At 16 missiles it increases to 100 ft, and so on. Or in other words, at every exponential power of 2, further increase the blast radius by the base radius. Someone else can math this up better than me I think.

Defending Against Missile Attacks

Counter-Volleys

One of the most effective defenses against missiles is with more missiles - that is, using your own missiles to counter those being fired at you. When one combatant has fired missiles into the fray, other combatants can attempt to blow the incoming missiles out of the sky before they hit their targets.
In order to attempt this, the prospective defender must meet all of the following reqs:

They must have Actions available to spend this round (i.e. they can't draw from next round's Action pool).

They must have one or more missiles of their own that can be immediately fired.

This requires spending an Action to attept the defensive volley. Roll the attack with your own missile(s), using the same rules as if you were attacking. Base target number is 9 for dumb missiles, 15 for smart missiles. If the incoming missiles are moving at a speed faster than the counter-missiles (see p. 363 RUE), increase the target number by the 100s digit of the difference in mph.
For example, if the incoming missile is a dumb Medium-Range Fragmentation (1000 mph) and the defending missile is Short-Range Fragmentation (450 mph), the target increase is [phone]=550) for a total target of 14 (9+5=14). However if the incoming missile were change to a smart Long-Range Nuclear missile (2010 mph) then the base target increase is [phone]=1560) for a whopping total target of 30! (15+15=30)
If the counter attack roll succeeds, then a missile in the attack has been hit! Roll damage for the base defensive missile if it destroys the incoming missile, then it has been intercepted, yay! If the attack is a volley, there's a chance the defensive missile detonated additional missiles in the volley. The defender rolls 1d100 plus 5 for each missile in their own volley:

01-20: Only the initial missile was hit, reducing the incoming damage multiple by 1.

21-40: 1d4 other missiles in the volley were taken out by the blast, reducing the incoming damage multiple by likewise.

41-60: 4d4 other missiles in the volley were taken out by the blast, reducing the incoming damage multiple by likewise.

61-100: The blast set off a chain reaction taking out all of the remaining missiles in the volley! Reduce incoming damage multiple to x0.

If any of the results reduce the multiple to x0 or lower, all of the incoming missiles are detonated before impact, doing no damage.
And yes, multiple defenders can simultaneously counter-volley against the same incoming missiles or volleys. Resolve these one at a time; if the first counter does not fully eliminate the attack, apply the next counter's possible results to the now-potentially-reduced incoming volley.

Dodging Missiles

Dodging Missiles is a dual consideration: you ultimately want to dodge both the point of impact and the inevitable blast radius. Such a feat is only feasible if your character somehow has the ability to rapidly move out of the missile's (or volley's) blast area. This is usually only possible if you are actively controlling a nimble and/or fast-moving vehicle that is already in motion.
Ultimately it's a decision up to the GM, based on the situation at hand. Should you meet the GM's requirements for this possibility, the actual dodge is handled with a normal dodge roll against the total strike roll of the missile attack - note that volleys are significantly higher, and thus more difficult to dodge.
Dodging a single missile requires only a single standard dodge Action to dodge both missile and blast radius in one go. If successful, you take no damage at all. If not, then the hit is dead on and you take full damage. This can be attempted by anyone that would be damaged by the missile,
Dodging a missile volley will likely require two or more standard dodge Actions to avoid - the first gets past the full-damage point of impact, and two or more may be required to also escape the extended half-damage blast radius. As with single missiles, only make a single roll regardless of the Action cost.
In either case, a Nat 20 on the attack requires a Nat 20 on the defense as well. This is the standard rule for Palladium defense actions, and is no different here.
Rolling with the Impact is also possible for some robots, power armor, and mega-damage beings, but only against explosive missiles. This is handled as normal, with a successful roll halving the damage taken.

Shooting Them Down

This is essentially the same as a counter-volley (see above), only you're using a ranged weapon to attempt to shoot down a single missile at a time. Each such shot requires spending an Action. However, the speed penalty for shooting a missile is significantly higher: use the full 100s digit of the missile's speed in mph! So a smart missile moving at 2000 mph would have a +20 target modifier, for a total of 35!
As with counter volleys, destroying a single missile in the volley both reduces the incoming damage multiple and can potentially detonate others, as detailed above.

Movement in Combat

Movement happens organically. For a simple abstraction, according to the RUE (and some application of basic math), your SPD score is effectively the number of feet tat you can move in one second of time. Since each combat pass is 5 seconds, then you can move your SPD score x5 in any one pass. Apply that before, during, or after your actions that turn as you see fit. I am not one to care about measuring exact distances, nor am I one to micromanage how many feet you have moved per action. If Movement ever comes into question, we'll deal with it then, make a call that fits the situation, and then move on.

Movement Penalties: According to RUE p. 361, "Shooting wild" applies when you are moving. Ignore this. Instead, use the same penalties as if the target were moving. So if you are moving and they are moving, the penalties to hit stack.

Dead-On Exceptions: The exception to this is if one or both of you are moving directly at each other. In such cases, apply only a single -1 movement penalty regardless of either of your speeds.

Max Speed Note: If you don't have the Running skill, then it takes a full melee Round of running from a stand still to work up to your max speed. During that first round you will be considered at half speed. If you do have the Running skill, then it takes only a full melee Phase to work up to max. If you have a special ability such as bionics, a juicer rig, or olympic sprinting skills, you can hit max speed immediately from a stand-still.

Unless I deem otherwise based on extreme situations, Movement in combat does not require the use of APMs, be you running, walking, swimming, or flying. Noteworthy exceptions to this are skill-required movements such as climbing and swimming. Since they are skills, you must spend the normal APM action cost for using skills unless you are have the movement as a natural ability (like a mer-man with an innate swimming SPD).

Damage Systems: SDC, minor MDC, and Major MDC

Updated July 2021: The damage systems are altered enough that I've moved them to their own dedicated sub-article: Damage Systems

Vehicle Combat Rules

Some clarifications on vehicle-based combat.
Controlling the Vehicle: A vehicle in motion must be actively controlled by a character. This character must dedicate one or more of their Actions each round to maintaining control of their vehicle.
Under "normal" speeds, a vehicle control roll is required on the first action of each such pilot on the first round of combat. If successful, they can maintain that result on each subsequent round without rolling, unless there is a notable change in circumstances. Qualifying changes include major speed adjustments, being rammed, changes in terrain, and so on.
The table below shows a basic expectation of how many Actions are required for vehicle control each round, and how often the pilot must roll to maintain control. Speeds are relative to the vehicle description's posted maximum speed.

Vehicle Speed	Base Target*	Roll Cadence	# Actions/Round
25% or lower	20	At start of combat, and at every change/maneuver	1
Up to 50%	40	At start of combat, and at every change/maneuver	1
Up to 75%	60	Every round and new maneuver	2
100%/Redline	80	Every round and new maneuver	3

*Base target is only based on speed. Other modifiers may apply from terrain, weather, etc.
Vehicular Maneuvers: The pilot can attempt any number of additional special maneuvers, mostly made up on the spot and applied as makes sense. Each such maneuver requires the pilot to spend an additional Action.
Vehicular Dodges: Most combat-focused vehicles like robots and power armor already have dodge values. However, sometimes a car or truck or other more conventional vehicle will be shot at, and its driver may wish to dodge. To do so, the driver must spend an additional Action as with any other dodge attempt. They then roll their relevant Pilot skill against 5x the attacker's attack roll total. If there would be any relevant ranged attack defense modifiers, also apply them at 5x.

Critical Failures

Rifts doesn't have any default built-in Crit Fail rules, and truth be told I've never really enjoyed implementing them. So here are my Nat 1 rules:
When you roll a natural 1 on an attack, the attack only misses if it would normally miss, i.e. your bonuses don't add enough to make the roll a success. In any case, success or failure, a "Nat 1" roll adds something unfortunate to the result. Resolve the outcome as normal, then narrate a consequential setback of some kind. The gun jams, the bowstring snaps, the sword slips from your grasp, your gauntlet catches awkwardly in the opponent's armor, your weapon takes some damage, and so on.
Note that this is not a "critical failure" in the classic sense. The Natural 1 does not necessitate an automatic failure, and can even be a success if you have enough roll bonuses to boost the result. And the setback happens regardless of a hit or a miss - in fact, if the roll is a miss, then the setback can be a way to narratively describe why you missed in the first place.