The Master, Multiplied + Cybermen Squadron + Encroaching Mycosynth + Combat Celebrant

The Master, Multiplied

Cybermen Squadron

Encroaching Mycosynth

Combat Celebrant

How it works

1. Declare Combat Celebrant as an attacker, choosing to exert it as it attacks.
2. Combat Celebrant's myriad and printed abilities trigger.
3. Resolve the myriad trigger, creating a token copy of Combat Celebrant attacking each other opponent.
4. Resolve the second trigger, causing you to untap all other creatures you control and to get an additional combat phase after this one.
5. Move to your next combat phase, not exiling the Combat Celebrant tokens due to The Master.
6. Repeat using a Combat Celebrant token that hasn't attacked this turn.