7. Keywords and effects
Ambush
Units that join a fight already going on
A unit is usually played in your own main phase, with nothing on the chain, to your base or a battlefield you control. A unit with has one more option: you can play it as a Reaction, to a battlefield where you have units.

That means it can arrive in the middle of a fight. Anywhere a Reaction could be played, with something on the chain or with focus in a showdown, you can play it into a battlefield where your units already are.
An example
On your opponent's turn, they move a (3 ) onto a battlefield where you have a Recruit (1 ). In the showdown, they pass focus to you.
- You play (3 ) to that battlefield, using its Ambush. It arrives exhausted, as units do, but exhausted units still fight.
- You both pass focus. The showdown ends, and the combat starts.
- Their 3 damage: 1 kills the Recruit, and the last 2 on Soulspinner aren't enough.
- Your 1 + 3 = 4 damage kills the Skulker. You keep the battlefield.
Without Soulspinner, the Skulker kills your Recruit and takes the battlefield.
On your own turn
Ambush works when you're the attacker too. Move your units onto your opponent's battlefield, and you have units there: in the showdown, you can Ambush another one in to join them.
A unit played with Ambush leaves the chain at once, like any unit. So your opponent can't answer the unit itself, only what comes after it.
Try it
Ambush a unit into a fight on your opponent's turn.
Set it up on the boardTry it
Ambush two units into the same chain, one after the other.
Set it up on the boardTry it
Ambush into the fight your own move starts, then follow up with an Action.
Set it up on the board