Infinite combat phasesInfinite magecraft triggersInfinite mana creatures you control can produceInfinite storm countInfinite untap of creatures you control
How it works
Declare Zethi as an attacker, attacking an opponent unable to block and kill it.
Zethi triggers.
Holding priority, activate all mana-producing creatures you control by tapping them, adding at least 3.
Resolve the Zethi trigger, causing you to pay 3 to cast a copy of Savage Beating.
Resolve the Savage Beating copy, untapping all creatures you control and causing you to get an additional combat phase after this one.