Impostor Syndrome, Combat Celebrant, and Fervor

Prerequisites

• Impostor Syndrome on the battlefield
• Combat Celebrant on the battlefield
• Fervor on the battlefield

Steps

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

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite combat phases
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinite combat damage