Combat Celebrant + Unforgiving One + Clone + Altar of Dementia + Mass Hysteria

Combat Celebrant

Unforgiving One

Clone

Altar of Dementia

Mass Hysteria

How it works

1. Declare Combat Celebrant and Unforgiving One as attackers, choosing to exert Combat Celebrant as it attacks.
2. Combat Celebrant triggers, untapping all other creatures you control and causing you to get an additional combat phase after this one.
3. Unforgiving One triggers, returning Clone from your graveyard to the battlefield as a copy of Combat Celebrant.
4. Activate Altar of Dementia by sacrificing Combat Celebrant, causing target player to mill cards equal to Combat Celebrant's power.
5. Move to your next combat phase.
6. Declare Clone and Unforgiving One as attackers, choosing to exert Clone as it attacks.
7. Clone triggers, untapping all other creatures you control and causing you to get an additional combat phase after this one.
8. Unforgiving One triggers, returning Combat Celebrant from your graveyard to the battlefield.
9. Activate Altar of Dementia by sacrificing Clone, causing target player to mill cards equal to Clone's power.
10. Repeat.