Infinite creature ETBInfinite creature LTBInfinite combat phasesInfinite creature tokens with hasteInfinite death triggersInfinite mana creatures you control can produceInfinite creature sacrifice triggersInfinite untap of creatures you control
How it works
Declare Grub and Combat Celebrant as attackers, choosing to exert Combat Celebrant as it attacks. Grub and Combat Celebrant trigger.
Resolve the Grub trigger, putting a -1/-1 counter on Combat Celebrant and then creating a tapped and attacking token copy of it.
Combat Celebrant dies as a state-based action due to having 0 toughness.
Resolve the Combat Celebrant trigger, causing you to untap all other creatures you control and causing you to get an additional combat phase after this one.
Repeat each combat phase, using the Combat Celebrant token instead.
This loop turns Combat Celebrant into an endless engine of extra combat phases by leveraging the unique attack trigger of Grub, Storied Matriarch. As Grub attacks, its ability blights Combat Celebrant—placing a -1/-1 counter on it that immediately sends the original Combat Celebrant to the graveyard as a state-based action, while simultaneously churning out a temporary token copy of it. Meanwhile, Purphoros, Bronze-Blooded quietly ensures that your entire swarm of attackers can rush straight into battle with haste the moment they arrive. Best of all, once the dust settles and Combat Celebrant rests in the graveyard, Grub can easily transform into Grub, Notorious Auntie during your main phase to pluck the fallen warrior right back out of your graveyard and back into your hand, ready to do it all over again.