The Master's
Codex
A reference guide to the core mechanics, conditions, and environmental rules that govern the world.
Core Mechanics
The fundamental engines that drive the game's resolution system.
Advantage & 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 you have either, you roll a second d20 when you make the roll.
- ✦Use the higher of the two rolls if you have advantage.
- ✦Use the lower roll if you have disadvantage.
- ✦If multiple situations affect a roll and each grants advantage or imposes disadvantage on it, you don't roll more than one additional d20. If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them.
Difficulty Class (DC)
For every ability check, the DM decides which of the six abilities is relevant to the task at hand and the difficulty of the task, represented by a Difficulty Class.
| Task Difficulty | DC Target |
|---|---|
| Very easy | 5 |
| Easy | 10 |
| Medium | 15 |
| Hard | 20 |
| Very hard | 25 |
| Nearly impossible | 30 |
Status Conditions
Conditions alter a creature's capabilities in a variety of ways and can arise as a result of a spell, a class feature, a monster's attack, or other effects.
Blinded
Charmed
Frightened
Grappled
Paralyzed
Poisoned
Prone
Restrained
Advanced Combat
Beyond simply rolling to attack, combat involves utilizing cover, understanding damage types, and fighting for your life when knocked down.
Cover
Walls, trees, creatures, and other obstacles can provide cover during combat, making it more difficult to harm a target.
Half Cover
+2 bonus to AC and Dexterity saving throws.
A target has half cover if an obstacle blocks at least half of its body. Examples: a low wall, a large piece of furniture, a narrow tree trunk.
Three-Quarters Cover
+5 bonus to AC and Dexterity saving throws.
A target has three-quarters cover if about three-quarters of it is covered by an obstacle. Examples: a portcullis, an arrow slit.
Total Cover
Can't be targeted directly by an attack or a spell.
A target has total cover if it is completely concealed by an obstacle.
Damage Types
Different attacks, damaging spells, and other harmful effects deal different types of damage. Damage types have no rules of their own, but other rules, such as damage resistance, rely on the types.
Physical
Bludgeoning, Piercing, and Slashing.
Elemental
Acid, Cold, Fire, Lightning, and Thunder.
Arcane/Divine
Force, Necrotic, Poison, Psychic, and Radiant.
Death Saving Throws
Whenever you start your turn with 0 hit points, you must make a special saving throw to determine whether you creep closer to death or hang onto life.
Roll a d20
If the roll is 10 or higher, you succeed. Otherwise, you fail. A success or failure has no effect by itself.
Three Strikes
On your third success, you become stable. On your third failure, you die.
Rolling 1 or 20
When you make a death saving throw and roll a 1 on the d20, it counts as two failures. If you roll a 20, you regain 1 hit point.
The Environment
The world is a dangerous place. Surviving means knowing when to rest, how to see in the dark, and how to avoid deadly hazards.
Resting
Heroic though they might be, adventurers can't spend every hour of the day in the thick of exploration, social interaction, and combat.
Short Rest
At least 1 hourA character can spend one or more Hit Dice to regain hit points. Some class features (like Warlock spell slots or Fighter Action Surge) are also regained.
Long Rest
At least 8 hoursA character regains all lost hit points and regains spent Hit Dice, up to a number of dice equal to half of the character's total number of them. Also restores all spell slots and long-rest abilities.