Actions
Most cards can only be played on your own turn, when nothing else is going on: no Showdown, nothing waiting to resolve. That's the normal timing.
[Action] is a keyword that gives a card extra permission: it can also be played during Showdowns, on any player's turn. It doesn't take any timing away, so you can still play it on your own turn like a normal card.
- On your turn: move in, and use an [Action] in the Showdown, once you've seen what you're fighting.
- On their turn: when they attack you, the Showdown before the damage is your window. An [Action] can change the fight before a single point of damage is dealt.
- Not while a spell is waiting on the Chain: for that you need [Reaction], the next lesson.
- Abilities can have it too, written "[Action] —" before the ability.
Your opponent attacks your battlefield. You hold Hextech Ray ([Action]) and Mobilize (no keyword). Which can you play in the Showdown?
- Hextech Ray: [Action]. Deal 3 to a unit at a battlefield.
- Cleave: [Action]. Give a unit [Assault 3] this turn, +3 Might while it's attacking.
- Mobilize has no [Action]: you can only play it on your own turn, outside Showdowns.
Words from this lesson
- [Action]
- Lets a card also be played during Showdowns, on either player's turn.
From the Core Rules (2026-10-09): 806 — Action · 307 — States of the Turn · 341 — Showdowns