Aerial Combat Mechanics

The following mechanics are from Arcadia Magazine: Issue #3. This work contains material that is copyright Wizards of the Coast and/or other authors.

Introduction

Aces High is a lightweight ruleset for aerial combat, aimed at replicating the high-octane action of a cinematic dogfight. Aerial combat doesn’t happen a lot in roleplaying games, because it tends to be more cumbersome and less fun than combat on the ground—but in many stories that aren’t RPGs, aerial battles happen all the time! The aim of Aces High is to emulate the thrill of those stories, and make you want to put more aerial combat in your games. These rules are strictly aimed at combat encounters that take place entirely in the air. No half measures.

The Flight Modifier

The cornerstone of Aces High is the flight modifier, a number attached to your character which functions like an ability modifier, and is used to modify d20 rolls. This includes ability checks, called flight checks, and saving throws, called flight saving throws.
The two factors that determine your flight modifier are size and flying speed, because the flight modifier is based on the real-life concept of the thrust-to-weight ratio. You can find a vehicle or creature’s flight modifier on the flight modifiers table on the next page.
When riding a mount, use the mount’s flight modifier. When piloting a vehicle, use the vehicle’s flight modifier. When you gain a flying speed, whether through a spell such as fly, or the use of a magic item such as wings of flying, calculate your own flight modifier.

Pilots and Passengers

If you’re the helmsman of a vehicle, directing a mount, or flying under your own steam, you’re considered a pilot. Only pilots use a flight modifier. If you’re riding along on a mount, vehicle, or magic item, but you’re not directly responsible for piloting, then you’re a passenger, and you don’t use any flight modifier. Don’t worry! You can still take actions during the action phase.

Example Flight Modifiers

Vessel	Flight Modifier
Orn	+2
Generation 1 Airship	+2
Generation 2 Airship	+3
Tiyruuk	+5
Generation 3 Airship	+7
Drekkan (Young)	+9
Generation 4 Airship	+11
Generation 5 Airship	+11
Drekkan (Elder)	+12
The Mistravindur	+13

Abstract Positions

Aces High aims to be fast, simple, and fun. Don’t worry about the precise positioning of combatants, the direction they are flying, or their fly speed! You can safely assume that combatants are constantly changing direction while chasing each other, automatically making the best maneuvers they can—the only thing you need to know is whether or not they have a clear shot at each other. Measurements, including altitude (see “Altitude Die”), are abstractions when using these rules. Using minis can be useful to help visualize the scene, but Aces High doesn’t use a grid at all.

How to Play

While you can defeat an opponent by dealing damage to them, your primary objective in an Aces High encounter is to ground the enemy. Knocking your foes out of the sky is the fastest path to victory!

Scramble!

When two or more combatants commit to aerial combat, all pilots involved must Scramble! Scrambling sets the turn order and the starting altitude of each combatant. Much like standard initiative, combatants roll a d20 and add their flight modifier to the result, with higher results taking their turns first. However, unlike initiative, all combatants have 5 seconds to roll as many times as they want, trying to get the best possible result. Once the timer is up, everyone must use the result they have in front of them! When flying any mount or vehicle, only the pilot needs to Scramble. Passengers don’t need to Scramble—they take actions when their pilot does.
When a new combatant joins (or rejoins!) the fray, they Scramble without a timer, and use the first result they roll. To find your opening altitude, don’t add your flight modifier; all you need to do is look at the number on your d20, and match it to the corresponding Altitude on the Opening Altitude Table.

Opening Altitude Table

D20	Altitude
1-4	2
5-8	3
9-12	4
13-16	5
17-20	6

Altitude Die

Altitude is vital to both success and survival in an Aces High encounter. We track it on the Altitude Die, a d6 that you can place next to your character sheet or your mini. The higher the number, the higher you are!
Being above your target is an enormous tactical advantage that allows you to use the sun or other environmental conditions to make tracking your movement extremely difficult. A pilot is too engaged with flying to spend precious seconds craning their neck to squint at the sky! You have disadvantage on attack rolls against targets of a higher Altitude than you, unless you’re a passenger. As you might expect, this also means you have advantage on attack rolls against targets with an Altitude below yours. This advantage applies whether you’re a pilot or a passenger.

The Stunt Phase

Once everyone has Scrambled and set their Altitude Die, play begins. On each player’s turn there are two phases; the stunt phase—in which you try to create angles of attack, and the action phase—in which you try to use them! When your stunt phase starts, you roll a number of d4s equal to your flight modifier (minimum of 1 die). These are your Stunt Dice. You can spend them to alter your Altitude, or spend them to create Angles. Unspent dice carry over to the next round. When your next stunt phase starts, roll a new set of d4s, and add them to the pile you had leftover. Your stunt phase ends when you say it does, or when you have no more Stunt Dice to spend.

Optional Rule: Burning Daylight!

Once you’re more comfortable with this system, you may want to turn up the heat. Try adding a 60-second timer to the stunt phase to add some pressure, if everyone in your group is okay with it. What’s more important to you; adjusting your Altitude, or creating an Angle? Choose fast!

Creating Angles

When you roll your Stunt Dice, the results are somewhat like a hand of cards. To create an Angle, you must match three-of-a-kind, or three-in-a-row. For example, 3-3-3 and 2-3-4 are both viable Angles. When you match and subsequently spend these dice, you gain an extra action to use during the action phase!

Multiple Angles

If you’re fast enough, it’s possible to create multiple Angles and therefore access more than the normal amount of actions in one turn, but only the fastest of creatures and vehicles can do this regularly! Generally speaking, it’s more likely that a monster that’s in their element when flying—like a roc, or a couatl—is going to be fast enough to really bend the action economy, but that’s by design; dogfighting a roc should feel like a legendary encounter!

Adjusting Altitude

The other way to spend Stunt Dice during your stunt phase is to adjust your Altitude, either by climbing or diving. In both cases, you spend a Stunt Die and then alter your Altitude by the number on the spent Stunt Die. Climbing increments the Altitude Die, and diving decrements it. You can only spend a Stunt Die to adjust your Altitude once during your stunt phase. When you choose to dive, the potential energy you’ve stored is transformed into momentum you can use to supercharge your speed! When you decrement your Altitude Die by the result of a spent Stunt Die, you can add that amount as a bonus to one of the following: 1. Your AC. 2. Your attack and damage rolls. You keep these bonuses until the start of your next turn.

High Altitude

Climbing above 6 on the Altitude Die means you’ve passed over into High Altitude. Upgrade your Altitude Die to a d12! For every point of Altitude you have above 6, you gain an extra Stunt Die to roll at the start of your stunt phase. You can’t climb above Altitude 12. However, any creature that ends its turn in High Altitude must make a Constitution saving throw to withstand the thinning air and plummeting temperature! Creatures that don’t need to breathe automatically succeed. The DC for a High Altitude Constitution saving throw is the number on your Altitude Die x 2. Any creature that fails this saving throw falls unconscious. This may or may not mean you start Freefalling, but it’s likely that it does—an unconscious creature cannot fly, and if you’re piloting a vehicle, you’ve probably passed out at the wheel. You can repeat this saving throw in order to regain consciousness at the end of each of your turns, but the DC for repeated saving throws remains the same no matter your Altitude. See “Freefall” below for more details.

Low Altitude

If your Altitude die shows a 1, then you are in Low Altitude, and just like High Altitude, it’s dangerous. If your Altitude die ever decrements below 1, or you’re in Freefall and you end your turn in Low Altitude, you hit the ground. And probably explode.If you end your turn in Low Altitude and you’re not Freefalling, make a Flight saving throw to avoid colliding with the ground, ocean, rooftops, lava, etc. The DC for this saving throw depends on the terrain, and so is determined by the GM. The sample encounter at the end of this article contains an example. Whenever you hit the ground, either by failing the Low Altitude saving throw, or by decrementing below 1 on the Altitude die, you immediately take falling damage, as described under “Freefall.”

The Action Phase

After your stunt phase ends, play moves into the action phase. During the action phase, you and any passengers with you on your mount or vehicle can take one action (except the Dash action) and one additional action for each Angle you created during the stunt phase. Passengers can also move about their vehicles, such as the deck of an airship, but pilots, mounts, and vehicles have used their movement during the stunt phase. If you’re a pilot, you can use an action to allow your mount or vehicle to take an action. This differs from how mounted combat works on the ground, chiefly because while airborne, you’re not using a movement speed or measuring distance in feet, both of which the core mounted combat rules heavily rely on.

Ranged Attacks and Melee Attacks

Ranged attacks and spells dominate in aerial combat. When you create an Angle, you can assume that you are putting yourself at an optimal distance to make any ranged attack you like. Melee weapons can be used so long as your Altitude dice matches your targets. If your weapon has the reach property, you can also make melee attacks against a target one point of Altitude away. Note that the normal Altitude rules for advantage and disadvantage still apply to reach weapons!

Taking Damage

Whenever you, your mount, or your vehicle is hit by an attack or fails a saving throw and takes damage as a result, decrement your Altitude by 1. Losing Altitude to damage can only occur once per turn. Note that this says once per turn, not once per round. For instance, each party member gets a chance to take the wyvern down a peg, but only once! Damage is typically applied to a mount or vehicle first, because it’s a much bigger target to hit in the midst of the chaos. A GM is free to rule that pilots and passengers can be directly targeted by attacks, potentially with disadvantage. If your vehicle or mount is reduced to 0 hit points and you don’t have a flying speed, you and any passengers without a flying speed begin Freefalling (see below).

Going Down

While reduced to less than half your hit points, you’re Going Down, and your Altitude decreases by 1 at the end of each of your turns, no matter what.

Direct Hit

When you score a critical hit on an attack, it’s a direct hit! The target rolls a d4, and drops that many points of Altitude immediately.

Knife-Fighting in a Phone Booth

The barbs of a grapnel bite into your hull! Two dragons lock onto each other with glittering jaws and teeth! Sometimes things get really up close and personal. When you want to grapple a target, it works as usual; in place of a melee attack. A GM might rule that grappling is necessary for a boarding action, if vehicles are involved! It’s up to the GM to decide whether or not grappling an opponent makes you both start Freefalling. A griffon grappling a pegasus might be grounds for such a ruling, but an airship firing a grappling hook probably wouldn’t!

Bugging Out

Sometimes you bite off more than you can chew—we’ve all been there—but how do you escape a foe that’s got you out maneuvered in the air? Turning tail and running isn’t so easy when they’ve zeroed in on you. As an action, you can decide to Bug Out. To do this, announce your intentions, and pray. You now have a giant target on your back, and every bandit in the sky is free to take a potshot at it! When you Bug Out, an enemy may use their reaction to make a Flight check against your passive Flight score, which is 10 + your Flight modifier. On a success, they can make a single spell or weapon attack against you. If you survive the onslaught, you escape, find somewhere to land, and live to fly another day.

Areas of Effect

If a fireball spell, dragon’s breath weapon, or other area of effect is used during an Aces High encounter, you can use your best judgement regarding which targets it can affect, or the rules for adjudicating areas of effect in the core rulebook, meant to guide GMs using theater-of-the-mind. As a basic guideline, creatures with an altitude difference of 3 or more cannot be included in the same area of effect.

Freefall

The core rules say that creatures take 1d6 bludgeoning damage for every 10 feet they fall, up to a maximum of 20d6 bludgeoning damage. In Aces High, normal rules for falling damage don’t apply. You always take 20d6 bludgeoning damage when you hit the ground, because you’re usually falling from extreme heights. A combatant flies so fast that touching the ground at all, outside of a controlled landing, is likely to spell disaster. Of course, a GM is free to rule that falling from Low Altitude deals less damage—something like 10d6, or 5d6—but these rulings should be made on instinct to keep the action moving!
This damage is applied to your mount or vehicle first if you have one (because they hit the ground first!), and leftover damage is then applied to you and your passengers. The pilot and passengers take the same amount of damage; it is not divided between them. If this seems harsh, consider the following; falling out of the sky is literally the worst case scenario when committing to aerial combat. Also note that this level of lethality becomes much less pronounced for player characters somewhere between levels 8 and 10, or once they have over 70 hit points total, as they’re less likely to suffer instant death. Even characters who are basically gods have succumbed to the unyielding wrath of gravity, but that said, those who want a bit of danger at lower levels should embrace it!

How Fast Do Things Fall?

Good question! Objects (and creatures!) in the real world hit terminal velocity after about twelve seconds of falling. For our purposes, that’s 2 rounds. When in Freefall, decrement your Altitude die once on round one, twice on round two, and then three times every round after that. This gives allies a window to Dive and save you! In order to do this, an ally must have a lower Altitude than you, and then must use an action to make a Flight check and snatch you from the jaws of death. The DC for this check is up to the GM, and could depend on how fast you are falling, how close to the ground you are, and even whether or not you need to be plucked from the deck of a failing airship! A GM could also use the speed at which a creature or vehicle is falling to help determine how much Freefall damage they take if no one is able to rescue them. For example, round one is 5d6, round two is 10d6, and round three and beyond is 20d6!

Gut Moves

Gut Moves are like reactions—you can make them whenever you want in response to a trigger, so long as you have some Stunt dice lying around unspent. Gut Moves do not use your Reaction.

On Your Six!

When an enemy makes an attack roll against an ally with the same Altitude as you, you can spend a Stunt Die to make an opposed Flight check against them. If you succeed, you can make one attack against them, adding the result to your attack and damage rolls.

Evasive Action!

When you take damage, you can spend a Stunt Die and gain that much Altitude immediately, instead of losing Altitude from the damage.

Back to the Taxpayers!

When an enemy adjusts their Altitude and passes you on the Altitude scale, you can spend a Stunt Die to make an opposed Flight check against them. If you succeed, you can move with them to corral them, pushing them further than they planned. You can push a target an amount up to the result of your spent Stunt die. When you push them, you move in step with them. Once your push has ended, the rest of their Altitude adjustment continues as normal.

Fangs Out!

During your action phase, you can spend a Stunt Die to target an enemy and make an opposed Flight check against them. On a success, make a single attack against them. On a failure, they make a single attack against you, adding the result of your spent Stunt die to their attack and damage rolls.

I Won’t Let You Down!

When an ally begins their Stunt phase, you can give them one of your unspent Stunt dice.