Reference

Actions, combat rules, conditions, skills, feats and languages. Search by name.

During play

Actions Every combat action and what it does: Attack, Dash, Disengage, Dodge and more.

Attack
Cast a Spell
Dash
Disengage
Dodge
Help
Hide
Ready

Conditions Every condition and what it does to a creature

Combat Rules Cover, advantage and the core combat rules

For your character

Feats Character feats from every source, with their prerequisites.

Alert
Lucky
Great Weapon Master
Sharpshooter

Skills Skills and the abilities behind them

Optional Features Eldritch invocations, maneuvers, metamagic and fighting styles

Languages From Common to Abyssal, with their scripts

Deities Gods by pantheon, with alignment, cleric domains and symbol

Combat Rules

Disadvantage

Source: XPHB

If you have Disadvantage on a D20 Test, roll two d20s and use the lower roll. A roll can't be affected by more than one Disadvantage, and Advantage and Disadvantage on the same roll cancel each other.