What happens if the attacker leaves the field during responses?
The attack fizzles. No combat happens and no combat damage is dealt.
Step by step
- Your opponent declares an attack with a 3-cost entity.
- Their When Attacking effects resolve first.
- In your response window you play Commune with Water and return the attacker to its owner’s hand.
- With no attacker left, the attack ends. Nothing is dealt, and you do not need to choose a Defender.
From the official game rules.
