Impostor Syndrome + Combat Celebrant + The Fire Crystal

Impostor Syndrome

Combat Celebrant

The Fire Crystal

How it works

1. Declare Combat Celebrant as an attacker, choosing to exert it as it attacks and triggering its ability, causing you to untap all other creatures you control and to get an additional combat phase after this one.
2. Deal combat damage to an opponent using Combat Celebrant, triggering Impostor Syndrome, creating a token copy of Combat Celebrant that isn't legendary.
3. During your next combat phase, declare Combat Celebrant and the Combat Celebrant token as attackers, choosing to exert the Combat Celebrant token as it attacks.
4. The Combat Celebrant token triggers, causing you to untap all other creatures you control and to get an additional combat phase after this one.
5. Repeat from step 2.

This clever combination achieves infinite combat phases by leveraging Combat Celebrant's exert ability to repeatedly grant extra combat steps. Whenever Combat Celebrant successfully damages an opponent, Impostor Syndrome steps in to clone it, ensuring you always have a fresh, un-exerted copy ready to attack again. Meanwhile, The Fire Crystal quietly supports the entire engine by granting your creatures haste so they can charge straight into battle the very turn they are copied.