Ready Action in D&D 5e (Explained): Triggers, Reactions, and Spell Timing
1 April 2026
The Ready action is how you say: “I don’t act now — I act when X happens.” It’s powerful, but it has trade-offs because it uses your reaction.
Related:
How the Ready action works (rules)
When you Ready:
- You choose a trigger you can perceive.
- You choose the action you’ll take when the trigger happens.
- When the trigger occurs, you use your reaction to do the readied action.
If you don’t use it before your next turn, it’s wasted.
Common good triggers
- “If the enemy comes through the doorway…”
- “If the monster tries to run…”
- “If the caster starts casting…”
Triggers that are too vague (“if anything happens”) usually get rejected by DMs — be specific.
Readying a spell (the big pitfall)
When you Ready a spell, you typically:
- Cast it on your turn and hold it,
- Then release it as a reaction when the trigger happens.
This means your concentration can matter:
FAQ
Can I Ready an attack and still take an opportunity attack?
No. Readying uses your reaction. If you spend your reaction on the readied action, you don’t have it for opportunity attacks (and vice versa).
Can I Ready “when the enemy does something”?
Your trigger needs to be specific and perceivable. “When they step through the doorway” works. “When they do something suspicious” is usually too vague.
What happens if my trigger never happens?
You don’t get the reaction attack/action, and the readied action is wasted when your next turn begins.
If I Ready a spell, do I spend the slot even if it never triggers?
At many tables, yes: you cast and hold it, so the slot is spent even if you never release it. This is one reason readied spells are risky.
Related rules to learn next
Recommended gear
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- Dice set (7-piece polyhedral) — Fast rolling, less sharing, fewer pauses.
- DM screen — Quick rules reference and cleaner pacing.
- Battle mat / grid map — Movement and AoE become instantly clear.