Infinite combat phasesInfinite untap of creatures you controlInfinite mana creatures you control can produceInfinite creature ETBInfinite creature tokens
How it works
Declare Combat Celebrant and Sandstorm Crasher as attackers, choosing to exert Sandstorm Crasher and Combat Celebrant as they attack. Combat Celebrant and Sandstorm Crasher each trigger.
Resolve the Sandstorm Crasher trigger, creating a token copy of Combat Celebrant that is tapped and attacking.
Resolve the Combat Celebrant trigger, untapping all other creatures you control and causing you to get an additional combat phase after this one.
Repeat during each combat phase using the Combat Celebrant token instead.