Combat Celebrant + Adarkar Valkyrie + Anger + Phyrexian Altar

Combat Celebrant

Adarkar Valkyrie

Anger

Phyrexian Altar

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 Phyrexian Altar by sacrificing Combat Celebrant, adding one mana of any color.
5. Combat Celebrant dies, triggering Adarkar Valkyrie, returning Combat Celebrant from your graveyard to the battlefield.
6. Repeat.