Combat Celebrant + Adarkar Valkyrie + Anger + Altar of Dementia

Combat Celebrant

Adarkar Valkyrie

Anger

Altar of Dementia

How it works

1. Activate Adarkar Valkyrie by tapping it, targeting Combat Celebrant.
2. Declare Combat Celebrant as an attacker, choosing to exert it as it attacks.
3. Combat Celebrant triggers, untapping all other creatures you control and causing you to get an additional combat phase after this one.
4. Activate Altar of Dementia by sacrificing Combat Celebrant.
5. Combat Celebrant dies, triggering Adarkar Valkyrie, returning Combat Celebrant from your graveyard to the battlefield.
6. Resolve the Altar of Dementia ability, causing target player to mill cards equal to Combat Celebrant's power.
7. Repeat.