The game determines the success of various actions by rolling dice for you and for other creatures in the game. The result of a die roll or dice roll is often modified by bonuses and penalties. Characters that are very skilled, use powerful items to enhance their abilities, or are under the effects of various empowering conditions (such as from spells or potions) will tend to roll higher numbers. Characters that are unskilled, don't have access to good equipment, or are under the effect of negative conditions, will instead tend to roll lower numbers.
Some rolls need to reach a certain value to be considered a success. This is called the Difficulty Class of the roll, and is usually done with a D20. Rolling a 1 on a D20 is referred to as a natural 1, and rolling 20 on a D20 is referred to as a natural 20. On some rolls, these can have special effects, such as automatically failing or succeeding the roll, ignoring Modifiers and Difficulty Class.
Karmic Dice
In Baldur's Gate 3 you can enable the option to use so-called Karmic Dice. This means that the game will avoid frustrating streaks of very low rolls in a row, and perhaps overly lucky streaks of very high rolls in a row. The exact algorithm is not presently known and may be changed between versions of the game.
Types of rolls
Beyond the general principles explained above, the details of rolls depend on the type of roll that is being made. Following are the types of rolls in the game.
Attack Roll
When a creature attacks another, it rolls a d20. The result is modified by its Ability Score Modifier and Proficiency Bonus. If the result matches or exceeds the Armor Class of the target, then the attack is successful. Otherwise, it's a failure; this could mean the attack was a miss, failed to hurt the target due to its armor, or the target was able to dodge or parry.
As a special case, a roll of 1 means that the attack fails regardless of bonuses and the target's Armor Class. This is called a Critical Miss. Likewise, a roll of 20 means the attack succeeds regardless of the target's Armor Class. This is called a Critical Hit. A critical hit also affects the result of the Damage Roll, though the details of how this will be implemented in the finished game are not known yet.
Attacks done with Weapons always use an Attack Roll to determine success. Some spells also use an Attack Roll to determine whether they hit their intended target (such as Fire Bolt or Eldritch Blast), though other spells hit the target automatically (such as Magic Missile or Fireball). A spell that hits its target automatically may allow the target to make a Saving Throw instead.
The Ability Score used for the Modifier depends on the type of attack that's being made. Melee and ranged weapon attacks use Strength or Dexterity, depending on the weapon. For spells, the Ability Score used for the Modifier generally depends on the class of the caster:
| Intelligence | Wisdom | Charisma |
|---|---|---|
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The Attack Roll should not be confused with the Damage Roll, which instead determines the amount of damage done to a target by a successful attack.
Damage Roll
A Damage Roll is performed when a successful attack is made, a spell hits a target, a trap is activated, and so on. The result determines the damage done, in terms of hit-points. This roll can involve any type and number of dice.
For example, a successful hit with a Dagger will lead to a d4 being rolled to determine the damage (referred to as 1d4 damage), whereas a successful attack with a Greatsword will lead to two d6 being rolled (referred to as 2d6) for a total damage of 2 to 12. Being caught in a Fireball will cause 8d6 points of damage, though a successful Saving Throw (see below) can reduce it to half.
For attacks made with weapons, the total value resulting from the roll is affected by the attacking creature's Ability Score Modifier and Proficiency Bonus. For the damage of spell attacks, no such modifiers apply.
Saving Throw
Various types of danger can be avoided by making a Saving Throw, also called a save. The creature rolls a d20, and adds its Ability Score Modifier and Proficiency Bonus. The source of danger determines the Difficulty Class of the save as well as the Ability Score that determines the Modifier. If the result of the roll matches or exceeds the Difficulty Class, the save succeeds.
If a creature casts a spell that forces another to make a save, the Difficulty Class is determined by the caster's Modifiers, with the following formula:
Difficulty Class = 8 + Ability Score Modifier + Proficiency Bonus
A successful save could mean completely avoiding negative effects, or it could mean halving the damage received. For example, successfully saving against a spike trap could mean that you take no damage at all because you've successfully evaded the spikes. On the other hand, if a Fireball is cast on you, be it by a spell caster or a magical trap, then a successful Saving Throw will merely cut the damage in half. Some effects don't allow for a Saving Throw at all, for example the damage taken from Magic Missile.
Depending on the Ability Score used for the Modifier, a Saving Throw may be referred to as a Strength Saving Throw, Dexterity Saving Throw, Constitution Saving Throw, and so on.
Ability Check
Various actions, other than attacking or making a save, still require the creature to make an attempt that may fail. The creature rolls a d20, and adds its Ability Score Modifier and possibly a Proficiency Bonus. The attempted action has a specific Difficulty Class which the result of the roll must match or exceed.
Ability Checks can be based purely on an Ability Score, in which case they can only benefit from the Ability Score Modifier, but not any Proficiency Bonus. More commonly, however, the check will be related to a specific Skill, which not only determines the Ability Score used for the Modifier, but also lets the creature use its Proficiency Bonus if it happens to be Proficient in that particular Skill. In this case, the check may be called a Skill Check rather than an Ability Check.
For example, when a trap is near a creature, the game rolls a Perception Skill Check (or Perception Check for short) to determine whether the creature notices the existence of the trap. (This is not to be confused with making a Saving Throw after the trap is activated.) Perception is related to Wisdom, so a creature with a high Wisdom score will gain a bonus. If the creature doesn't gain any bonus from Wisdom, it could still gain a bonus from being Proficient in the Perception Skill. If the creature both has high Wisdom and is also proficient in Perception, it will gain both bonuses.
Once a trap is seen, the creature may want to disarm it. This will require a Sleight of Hand Check, which is related to Dexterity. So, a creature that both has high Dexterity, and Proficiency in Sleight of Hand, can benefit from both types of bonuses when attempting to disarm the trap.
| Strength | Dexterity | Intelligence | Wisdom | Charisma |
|---|---|---|---|---|
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(There are no Skills based on Constitution.)
Contest
A special type of Ability Check is called the Contest, in which two creatures both roll an Ability Check or Skill Check to contest each other, and one wins over the other. The creatures don't necessarily roll the same type of check.
An example of this is the Shove action, where the creature attempting the Shove must roll Athletics, and the defending creature is allowed to roll either Athletics or Acrobatics to contest the Shove. If the attacker's roll is higher than the defender's, the Shove succeeds, otherwise it fails.
Modifiers
Rolls can be affected by various bonuses and penalties. These can take the form of adding or subtracting a value from the result, or requiring two rolls instead of one and taking the lower or higher of the two values.
Advantage / Disadvantage
In various situations, a creature can have Advantage or Disadvantage on an Attack Roll, Saving Throw, or Ability Check.
Advantage simply means that you make the roll twice, and use the higher result. Disadvantage simply means you make the roll twice, and use the lower result.
Advantage and Disadvantage can cancel each other out. However, they cannot stack, meaning that you never roll more than twice.
Examples of situations that grant Advantage:
- Having the higher ground while making an attack
- Being unseen by the enemy while making an attack
- Various spells and abilities that grant Advantage
Examples of situations that grant Disadvantage:
- Trying to attack an enemy on higher ground
- Trying to attack an enemy obscured by darkness
- Various spells and abilities that grant Disadvantage
Ability Score Modifier
A creature's Ability Scores can modify the result of rolls, depending on how high or low the Ability Score is. Which Ability Score is used to determine the Modifier depends on the roll that's being made. The Ability Score Modifier for a specific Ability Score can be also be referred to by the name of that Ability Score, such as: Strength Modifier, Dexterity Modifier, etc.
| Score | Modifier |
|---|---|
| 1 | -5 |
| 2-3 | -4 |
| 4-5 | -3 |
| 6-7 | -2 |
| 8-9 | -1 |
| 10-11 | +0 |
| 12-13 | +1 |
| 14-15 | +2 |
| 16-17 | +3 |
| 18-19 | +4 |
| 20-21 | +5 |
| 22-23 | +6 |
| 24-25 | +7 |
| 26-27 | +8 |
| 28-29 | +9 |
| 30 | +10 |
For Attack Rolls
Weapon attacks will generally use Strength or Dexterity, depending on the weapon and the type of attack made. Melee weapons use the Strength Modifier, unless they have the Finesse property (such as Dagger or Rapier), in which case Dexterity can be used instead. The same rules apply to melee weapons with the Thrown property (such as Dagger or Handaxe) when they're thrown for a ranged attack: they use the Strength modifier, unless they have both Thrown and Finesse (such as Dagger), in which case Dexterity can be chosen again. Regular ranged weapons (such as Bows and Crossbows) always use Dexterity.
Spell attacks will use an Ability Score depending on the Class of the creature making it; see table above, under the section #Attack Roll.
For Damage Rolls
For Weapon attacks, the exact same rules apply to Damage Rolls as for Attack Rolls. If the Damage Roll involves multiple dice, such as the 2d6 damage of a Greatsword, then the Modifier is applied to the total value, not to each individual die roll.
For spell attacks, there is generally no Ability Score Modifier for the Damage Roll. The damage of spell attacks is increased through other means. For example, Cantrips such as Fire Bolt automatically become stronger as the caster reaches higher levels, and spells that expend spell slots can be cast at a higher level (expending a higher level spell slot) to increase their damage. The details depend on the individual spell in question.
For Saving Throws
For saves against specific spells and conditions, the spell or condition in question determines which Ability Score is used to make the save. For example, the Web spell requires you to make a Dexterity save, whereas Crown of Madness requires a Wisdom save. As with most spells and effects related to poison, Poison Spray requires a Constitution saving throw.
For Ability Checks
Which Ability Score is used for an Ability Check depends on the category or type of Ability Check, such as Athletics, Sleight of Hand, History, Perception, Deception, and so on. See the table above, under the section #Ability Check, for the different categories and which Ability Score they use for the Modifier.
Proficiency Bonus
Creatures can have Proficiency in a number of talents, which grant them bonuses on various rolls. Proficiencies can be granted by a creature's Background, Race, Class, and Feats chosen when leveling up.
| Level | Proficiency Bonus |
|---|---|
| 1 to 4 | + 2 |
| 5 to 8 | + 3 |
| 9 to 12 | + 4 |
| 13 to 16 | + 5 |
| 17 to 20 | + 6 |
For Attack Rolls
Attack Rolls made with Weapons can benefit from Proficiency with the type of weapon that's being used. This kind of Proficiency can be granted by the creature's Race, Class, or Feats chosen when leveling up.
Weapon Proficiency may apply to a specific type of weapon, like Longswords, or a category of weapons, like Martial Weapons. For example, all High Elves and Wood Elves, regardless of their class, have a specific Proficiency in Longswords, Shortswords, Longbows, and Shortbows. On the other hand, Fighters have Proficiency in the entire categories of both Simple and Martial Weapons. Clerics have Proficiency in the category of Simple Weapons, whereas Wizards only have Proficiency in Quarterstaves, Daggers, and Light Crossbows.
Attack Rolls made for spells benefit from Proficiency in spell casting, which all creatures capable of casting spells have. The creature could have spell casting capabilities due to its Class, or from a Feat it chose when leveling up.
The lack of Proficiency in spell casting becomes apparent when you give a scroll such as Scroll of Guiding Bolt to a character that can't otherwise cast spells. Since Guiding Bolt uses an Attack Roll, but the character is not proficient in spell casting, they will have a lower chance to hit targets with the Guiding Bolt.
For Damage Rolls
Damage Rolls cannot benefit from Proficiency.
For Saving Throws
You can have Proficiency in a specific kind of Saving Throw, like Strength Saving Throw, Dexterity Saving Throw, and so on. Each Class has Proficiency in two such types of Saving Throws.
In addition, a creature can have Proficiency in more specific kinds of Saving Throws. For example, Elves have Proficiency in Saving Throws against being Charmed due to their innate Fey Ancestry trait.
Besides affecting the Saving Throws a creature makes to save itself, the Proficiency Bonus of a creature also affects the Difficulty Class of Saving Throws it imposes on others, such as by casting spells against them. The formula for this is: 8 + Ability Score Modifier + Proficiency Bonus
For Ability Checks
An Ability Check may be based directly on an Ability Score rather than a Skill, in which case no Proficiency Bonus is possible. If it's based on a Skill, however, a creature will get a Proficiency Bonus in the corresponding Skill Checks if it's Proficient in that Skill.
Proficiency in a Skill can be granted by Race, Class, or a Feat chosen when leveling up. For example, all Elves have an innate feature called Keen Senses which grants them Proficiency in Perception. Wood Elves have an additional feature called Mask of the Wild, which gives them Proficiency in Stealth. Rangers can gain Proficiency in a number of skills based on specific class features they choose: Bounty Hunter grants Proficiency in Investigation, Keeper of the Veil and Mage Breaker both grant Proficiency in Arcana, and so on. The Skilled Feat, if chosen when leveling up, allows a creature to gain Proficiency in any three Skills.