Brudiclad, Telchor Engineer + Combat Celebrant + Sublime Epiphany

Steps

1. Cast Sublime Epiphany by paying {4}{U}{U}, creating a token copy of Combat Celebrant.
2. At the beginning of your combat phase, Brudiclad triggers, creating a 2/1 Phyrexian Myr creature token, then choosing to have all tokens you control become copies of the Combat Celebrant token.
3. Declare one of the Combat Celebrant copy as an attacker, choosing to exert it as it attacks.
4. The Combat Celebrant copy triggers, untapping all other creatures you control and causing you to get an additional combat phase after this one.
5. Repeat from step 2.