As a whole, the game makes copious use of percentage and probability generators with an ancient and longstanding value: dice.
There are several different kinds of rolls when playing the game. For example, you already did the Ability Score rolls if you used dice for that.
You generate hit points using different dice, and when you make attacks, you will use dice to strike and dice for damage.
The basis of many rolls is a D20 Check – a basic roll.
To make a D20 Check, roll a d20 and add the relevant modifiers called for, apply bonuses and penalties and compare the total to the target number. If the total equals or exceeds the target number, the ability check is a success—the creature overcomes the challenge at hand. Otherwise, it’s a failure, which means the character or monster makes no progress toward the objective or makes progress combined with a setback determined by the GM.
Advantage and Disadvantage
Sometimes a special ability or spell tells you that you have Advantage or Disadvantage on an ability check, a saving throw, or an attack roll. When that happens, you 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 a 17 and a 5, you use the 5. If you instead have Advantage and roll those numbers, you use the 17.
If multiple situations affect a roll and each one grants Advantage or imposes Disadvantage on it, you don’t roll more than one additional d20. If two favorable situations grant Advantage, for example, you still roll only one additional d20.
If circumstances cause a roll to have both Advantage and Disadvantage, you are considered to have 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.
When you have Advantage or Disadvantage and something in the game lets you reroll the d20, you can reroll only one of the dice. You choose which one.
You usually gain Advantage or Disadvantage through the use of special abilities, actions, or spells. Inspiration can also give a character Advantage. The GM can also decide that circumstances influence a roll in one direction or the other and grant Advantage or impose Disadvantage as a result.
Modifiers
Proficiency Degrees exist from None to Expert, and greater skill will add a degree of modifier to any roll. One way to look at this is that modifiers are often more important than the base roll they modify.
Proficiency Bonus
Characters have a proficiency bonus determined by level. Monsters also have this bonus, which is incorporated in their stat blocks. The bonus is used in the rules on ability checks, saving throws, and attack rolls. It is not used on proficiency checks.
Your proficiency bonus can’t be added to a single die roll or other number more than once. For example, if two different rules say you can add your proficiency bonus to a Wisdom saving throw, you nevertheless add the bonus only once when you make the save.
Occasionally, your proficiency bonus might be multiplied or divided (doubled or halved, for example) before you apply it. For example, the rogue’s Expertise feature doubles the proficiency bonus for certain ability checks. If a circumstance suggests that your proficiency bonus applies more than once to the same roll, you still add it only once and multiply or divide it only once.
By the same token, if a feature or effect allows you to multiply your proficiency bonus when making an ability check that wouldn’t normally benefit from your proficiency bonus, you still don’t add the bonus to the check. For that check your proficiency bonus is 0, given the fact that multiplying 0 by any number is still 0.
For instance, if you lack proficiency in the History skill, you gain no benefit from a feature that lets you double your proficiency bonus when you make Knowledge (History) checks.
In general, you don’t multiply your proficiency bonus for attack rolls or saving throws. If a feature or effect allows you to do so, these same rules apply.
Ability Checks
An ability check tests a character’s or monster’s innate talent and training in an effort to overcome a challenge. The GM calls for an ability check when a character or monster attempts an action (other than an attack) that has a chance of failure. When the outcome is uncertain, the dice determine the results.
For every ability check, the GM decides which of the six abilities is relevant to the task at hand and the difficulty of the task, represented by a Difficulty Class. The more difficult a task, the higher its DC.
Contests
Sometimes one character’s or monster’s efforts are directly opposed to another’s. This can occur when both of them are trying to do the same thing and only one can succeed, such as attempting to snatch up a magic ring that has fallen on the floor. This situation also applies when one of them is trying to prevent the other one from accomplishing a goal— for example, when a monster tries to force open a door that an adventurer is 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 character or monster 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 monster trying to open a door and an adventurer 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 or monster is at risk of harm.
To make a saving throw, roll a d20 and add the appropriate ability modifier. For example, you use your Dexterity modifier for a Dexterity saving throw.
A saving throw can be modified by a situational bonus or penalty and can be affected by Advantage and Disadvantage, as determined by the GM.
Each class gives proficiency in at least three saving throws. These are Represented by the Ability Scores of that class, and all classes have three scores.
The wizard, for example, is proficient in Knowledge saves. As with skill proficiencies, proficiency in a saving throw lets a character add his or her proficiency bonus to saving throws made using a particular ability score. Some monsters have saving throw proficiencies as well.
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 (Mana Score) and proficiency bonus.
The result of a successful or failed saving throw is also detailed in the effect that allows the save.
Usually, a successful save means that a creature suffers reduced or sometimes no harm from an effect.
Spell Attack Saves
Spell Attack saves always trigger off of the Spell Caster’s Mana score.
Weapon Saves
If an ability calls for a save against Weapon DC, calculate this DC with the following formulas:
- Melee Weapon: 8 + Strength Modifier + Proficiency Bonus
- Range Weapon: 8 + Dexterity Modifier + Proficiency Bonus
Null Saves
Nulls always add their proficiency bonus and their Null bonus to their Mana Saves to resist magical effects. Note that the only Nulls are Warriors, Vanguards, and Outlaws.
Spell Effect Saves
Spell Effect saves are either described in the effect, or they will rely on the appropriate score:
Arcane: Knowledge.
Mystical: Perception.
Divine: Wisdom.
Eldritch: Sanity.
Primal: Charisma.
Psychic: Psyche.
Corruption: Heart.
Necrotic: Vitality.
Critical Hits & Fumbles
Critical Hits and Fumbles only apply to attack rolls. They are entirely Optional, and they do not work well in a game where something can have an Armor Class of 30.
When you score a Critical Hit (a natural roll of 20 plus modifiers that is still able to hit), the damage you do is also applied to the AC of the target, reducing their AC. Roll all of the attack’s damage dice, add any relevant modifiers as normal.
Higher quality objects have a save against the Critical: Adept quality gains a +1, Master Quality gains a +2, and Grand master gains a +3. The DC of this save is 10.
In terms of how to narrate this, armor falls off or splits, hide breaks open and a grievous wound appears, and more. This applies to both Monsters and PCs
A Critical Fumble (a natural roll of 1, without modifiers) results in the attacker’s weapon breaking. This also applies to both monsters and PCs.
Novice and Yeoman products do not get a save, but Adept, Master, and Grand Master quality items do get a save, adding their bonus of +1, +2, and +3 to the roll for each of their degrees of quality.
Magic weapons get a save. Magic armor also gets a save. The DC in both cases is a 10 minus the weapon/armor bonus and they always add the Grand Master bonus of +3 as well.
Skills
Each ability covers a broad range of capabilities, including skills that a character or a monster can be proficient in. A skill represents a specific aspect of an ability score, and an individual’s proficiency in a skill demonstrates a focus on that aspect. (A character’s starting skill proficiencies are determined at character creation, and a monster’s skill proficiencies appear in the monster’s stat block.)
For example, a Dexterity check might reflect a character’s attempt to pull off an acrobatic stunt, to palm an object, or to stay hidden. Each of these aspects of Dexterity has an associated skill: Acrobatics, Sleight of Hand, and Stealth, respectively. So, a character who has proficiency in the Stealth skill is particularly good at Dexterity checks related to sneaking and hiding.
Sometimes, the GM might ask for an ability check using a specific skill—for example, “Make a Piloting check.” At other times, a player might ask the GM if proficiency in a particular skill applies to a check. In either case, proficiency in a skill means.
Normally, your proficiency in a skill applies only to a specific kind of ability check. Proficiency in Athletics, for example, usually applies to Strength checks. In some situations, though, your proficiency might reasonably apply to a different kind of check. In such cases, the GM might ask for a check using an unusual combination of ability and skill, or you might ask your GM if you can apply a proficiency check to a different check. For example, if you have to swim from an offshore island to the mainland, your GM might call for a Constitution check to see if you have the stamina to make it that far. In this case, your GM might allow you to apply your proficiency in Athletics and ask for a Constitution (Athletics) check.
So, if you’re proficient in Athletics, you apply your proficiency bonus to the Constitution check just as you would normally do for a Strength (Athletics) check. Similarly, when your half-orc barbarian uses a display of raw strength to intimidate an enemy, your GM might ask for a Strength (Intimidation) check, even though Intimidation is normally associated with Charisma.
Working Together
Sometimes two or more characters team up to attempt a task. The character who’s leading the effort—or the one with the highest ability modifier—can make an ability check with Advantage, reflecting the help provided by the other characters.
In combat, this requires the Help action.
A character can only provide help if the task is one that he or she could attempt alone. For example, trying to open a lock requires proficiency with thieves’ tools, so a character who lacks that proficiency can’t help another character in that task. Moreover, a character can help only when two or more individuals working together would actually be productive. Some tasks, such as threading a needle, are no easier with help.
Group Checks
When a number of individuals are trying to accomplish something as a group, the GM might ask for a group ability check. In such a situation, the characters who are skilled at a particular task help cover those who aren’t.
To make a group ability check, everyone in the group makes the ability check. If at least half the group succeeds, the whole group succeeds. Otherwise, the group fails.
Group checks don’t come up very often, and they’re most useful when all the characters succeed or fail as a group. For example, when adventurers are navigating a swamp, the GM might call for a group Wisdom (Survival) check to see if the characters can avoid the quicksand, sinkholes, and other natural hazards of the environment. If at least half the group succeeds, the successful characters are able to guide their companions out of danger.
Otherwise, the group stumbles into one of these hazards.
