When the outcome of an action is uncertain, the game uses a d20 roll to determine success or failure. These rolls are called d20 Tests, and they come in three kinds: ability checks, saving throws, and attack rolls. They follow these steps:
- Roll 1d20. You always want to roll high. If the roll has Advantage or Disadvantage (described later in this chapter), you roll two d20s, but you use the number from only one of them—the higher one if you have Advantage or the lower one if you have Disadvantage.
- Add Modifiers. Add these modifiers to the number rolled on the d20:
- The Relevant Ability Modifier. This chapter and the Rules Glossary explain which ability modifiers to use for various d20 Tests
- Your Proficiency Rank Bonus If Relevant. Each creature can have Proficiency Ranks, which provide a bonus added when making a d20 Test that uses something, such as a skill, in which the creature has Proficiency Ranks.
- Circumstantial Bonuses and Penalties. A class feature, a spell, or another rule might give a bonus or penalty to the die roll.
- Compare the Total to a Target Number. If the total of the d20 and its modifiers equals or exceeds the target number, the d20 Test succeeds. Otherwise, it fails. The Game Master determines target numbers and tells players whether their rolls are successful. The target number for an ability check or a saving throw is called a Difficulty Class (DC). The target number for an attack roll is called an Armor Class (AC), which appears on a character sheet or in a stat block (see the Rules Glossary).
Advantage and Disadvantage
Sometimes a d20 Test is modified by Advantage or Disadvantage. Advantage reflects the positive circumstances surrounding a d20 roll, while Disadvantage reflects negative circumstances.
You usually acquire Advantage or Disadvantage through the use of special abilities and actions. The GM can also decide that circumstances grant Advantage or impose Disadvantage.
Roll Two D20s
When a roll has either Advantage or Disadvantage, roll a second d20 when you make the roll. Use the higher of the two rolls if you have Advantage, and use the lower roll if you have Disadvantage. For example, if you have Disadvantage and roll an 18 and a 3, use the 3. If you instead have Advantage and roll those numbers, use the 18.
They Don’t Stack
If multiple situations affect a roll and they all grant Advantage on it, you still roll only two d20s. Similarly, if multiple situations impose Disadvantage on a roll, you roll only two d20s.
If circumstances cause a roll to have both Advantage and Disadvantage, the roll has neither of them, and you roll one d20. This is true even if multiple circumstances impose Disadvantage and only one grants Advantage or vice versa. In such a situation, you have neither Advantage nor Disadvantage.
Interactions with Rerolls
When you have Advantage or Disadvantage and something in the game lets you reroll or replace the d20, you can reroll or replace only one die, not both. You choose which one.
Degrees of Success and Failure
In many cases, the outcome of a d20 Test isn't a binary success or failure. When an effect lists different outcomes in the case of a Major Success or Major Failure, use the Degree of Success table to determine which outcome occurs. A Major Success represents a result well above expectations, while a Major Failure represents a significant misstep. If a rule doesn't refer to degrees of success, treat the result as a normal success or failure regardless of how high or low the roll is.
Degree of Success
Ability Checks
An ability check represents a creature using talent and training to try to overcome a challenge, such as forcing open a stuck door, picking a lock, entertaining a crowd, or deciphering a cipher. The GM and the rules often call for an ability check when a creature attempts something other than an attack that has a chance of meaningful failure. When the outcome is uncertain and narratively interesting, the dice determine the result.
Ability Modifier
An ability check is named for the ability modifier it uses: a Strength check, an Intelligence check, and so on. Different ability checks are called for in different situations, depending on which ability is most relevant. See the Ability Check Examples table for examples of each check’s use.
Ability Check Examples
| Ability | Make a Check To... |
|---|
| Strength | Lift, push, pull, or break something |
| Constitution | Push your body beyond normal limits |
| Dexterity | Move nimbly, quickly, or quietly |
| Intelligence | Reason or remember |
| Wisdom | Notice things in the environment or in creatures’ behavior |
| Charisma | Influence, entertain, or deceive |
Difficulty Class
The Difficulty Class of an ability check represents the task’s difficulty. The more difficult the task, the higher its DC. The rules provide DCs for various checks, and the GM sets any DCs not explicitly provided. The Typical Difficulty Classes table presents a range of possible DCs for ability checks.
Typical Difficulty Classes
| Task Difficulty | DC |
|---|
| Trivial |
5 |
| Easy |
10 |
| Moderate |
15 |
| Challenging |
20 |
| Very Challenging |
25 |
| Heroic |
30 |
| Legendary |
35 |
| Nearly Impossible |
40 |
Proficiency Bonus
Cumulative Ability Checks
In most cases, when you make an ability check, there is an immediate consequence based on the check's success or failure. However, in cases where the consequences of your actions may not be seen for some time, a cumulative ability check can be used.
Instead of making a single ability check to determine success, you make a series of checks, choosing an ability relevant to the task as normal, and accumulating the results from several rolls, until a certain threshold of success is achieved. The GM sets a threshold or target number that needs to be reached as usual, this number is the Completion Difficulty (CD). The result of each roll is recorded and contributes to the overall progress towards the CD. As with a standard ability check, a more complex task has a higher CD.
A cumulative ability check may have multiple CD thresholds that yield progressively better results.
For example, William, wants learn more about vampires, specifically how to become one. He spends some time researching at a library. The GM has him roll an Intelligence (Investigation) check at the end of each day, recording each roll and revealing if William has found anything relevant to his goals. Once his cumulative total reaches 20 or more, William learns a little bit about famous vampires throughout history (uncommon but not obscure information). Once his total reaches 35 or more, William learns about a vampire's weaknesses and strengths, and at a cumulative total of 50, William finally uncovers how specifically someone becomes a vampire.
Passive Checks
A passive check is a special kind of ability check that doesn't involve any die rolls. Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the GM wants to secretly determine whether the characters succeed at something without rolling dice, such as noticing a hidden monster.
Your total for a Passive Check = 10 + all modifiers that normally apply to the check
If you have advantage on the check, add 5. For disadvantage, subtract 5. The game refers to a passive check total as a
rating.
For example, if a 1st-level character has a Wisdom of 15 and proficiency in Perception, he or she has a passive Wisdom (Perception) rating of 14.
Contests
Sometimes your efforts are directly opposed to another creature. This can occur when both you and the other creature are trying to do the same thing and only one can succeed, such as attempting to snatch up a magic ring that has fallen to the floor. This situation also applies when one of you is trying to prevent the other one from accomplishing a goal—for example, when a creature tries to force open a door that you are holding closed. In situations like these, the outcome is determined by a special form of ability check, called a contest.
Both participants in a contest make ability checks appropriate to their efforts. They apply all appropriate bonuses and penalties, but instead of comparing the total to a DC, they compare the totals of their two checks. The participant with the higher check total wins the contest. That participant either succeeds at the action or prevents the other one from succeeding.
If the contest results in a tie, the situation remains the same as it was before the contest. Thus, one contestant might win the contest by default. If two characters tie in a contest to snatch a ring off the floor, neither character grabs it. In a contest between a creature trying to open a door and another creature trying to keep the door closed, a tie means that the door remains shut.
Saving Throws
A saving throw—also called a save—represents an attempt to resist a spell, a trap, a poison, a disease, or a similar threat. You don't normally decide to make a saving throw; you are forced to make one because your character is at risk of harm.
Difficulty Class
The Difficulty Class for a saving throw is determined by the effect that causes it. For example, the DC for a saving throw allowed by a spell is determined by the caster's spellcasting ability and proficiency bonus.
A save's is also detailed in the effect that allows the save. Usually, a successful save means that a creature suffers no harm, or reduced harm, from an effect. If you don't want to resist an effect, you can always choose to fail the save without rolling.
The Three Saves
There are three types of saving throws, which are used to resist different kinds of effects:
Fortitude saving throws to resist the effects of abilities and afflictions that can debilitate the body. Fortitude saves use your Strength and Constitution modifier added together.
Reflex saving throws to respond quickly to a situation and how deftly you can avoid effects that have been thrown at you. Reflex saves use your Dexterity and Intelligence modifier added together.
Will saving throws to resist attacks to your mind and spirit. Will saves use your Wisdom and Charisma modifier added together.
If one of your Ability Modifiers is negative, it will contribute negatively to your overall save result when the two modifiers relevant to the save are added together. A saving throw can also be modified by a situational bonus or penalty and can be affected by Advantage and Disadvantage, as determined by the GM.
Proficiency Bonus
You add your Proficiency Bonus to your saving throw if you have proficiency in that kind of save (explained later in this chapter).
Repeat with Hope
Some debilitating effects allow you to repeat the Saving Throw against their effects after a certain duration, such as at the end of each of your turns. If the effect specifies that you repeat the save with Hope, you gain a +2 bonus to the result of your save for each repeated attempt, after the first.
For example, if you’ve been paralyzed by a caster’s
Hold Person spell, which allows you to repeat the save with Hope at the end of each of your turns, you gain +2 to your next save to shake off the effect, then +4 on your subsequent attempt, and so on until the effect ends.
This bonus is doubled when attempting to overcome effects applied to you by a creature whose Level is less than half of your own. For instance, a Level 10 Gladiator attempting to resist a Level 3 Wizard’s Hold Person after failing the first time would get a +4 on the Gladiator’s second Will save, a +8 on his third save, and so on.
Attack Rolls
An attack roll determines whether your attack hits a target. An attack roll hits if the roll meets or exceeds the target's Armor Class (AC). Attack rolls mainly occur in battle, and the effects that follow a hit are described in the Combat section, later in this chapter. If there's ever any question whether something you're doing counts as an attack, the rule is simple: if you're making an attack roll, you're making an attack.
Ability Modifier
You add your ability modifier to attack rolls, choosing a different modifier for different types of attack rolls:
Melee Attack. Making a melee attack with a weapon or an Unarmed Strike uses your Strength modifier.
Ranged Attack. Making a ranged attack with a weapon uses your Dexterity modifier.
Spell Attack. Making a spell attack uses your Spellcasting modifier, which varies depending on the spellcaster's spellcasting feature.
Proficiency Bonus
You add your Proficiency Bonus to your attack roll when you attack using spells, or using weapons that you have proficiency with. Weapon proficiencies are explained alongside skill and tool proficiencies later in this chapter.
Armor Class
A creature's Armor Class (AC) represents how difficult they are to hit. All creature's start by using the same basic AC calculation:
Base Armor Class (AC) = 10 + the creature's Dexterity modifier
A creature's AC can be modified by armor, spells, class features, any many other game elements. Many of these might allow you to increase your AC above your Base AC, but you can have
Only One Base AC.
Some spells and class features allow you to use a different way to calculate your Base AC altogether. If you have access to multiple features that give different ways to calculate your Base AC, you must which one to use; only one base calculation can be in effect for a creature.
Rolling 1 or 20
If the d20 roll for an attack is a 20 (called a "natural 20", indicating the highest possible roll), the attack hits regardless of any modifiers or the target's AC. This is called a critical hit, and is further explained in the Combat section,, later in this chapter.
If the d20 roll for an attack is a 1 (a "natural 1", indicating the lowest possible roll), the attack misses regardless of any modifiers or the target's AC.
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