Luxurious Locomotive + Ruthless Technomancer + Combat Celebrant + Umbral Collar Zealot

Luxurious Locomotive

Ruthless Technomancer

Combat Celebrant

Umbral Collar Zealot

How it works

1. Activate Luxurious Locomotive's crew ability by tapping seven creatures you control with total power 1 or greater, causing Luxurious Locomotive to become an artifact creature until end of turn.
2. Declare Luxurious Locomotive and Combat Celebrant as attackers, choosing to exert Combat Celebrant as it attacks, triggering their abilities.
3. Resolve the Luxurious Locomotive trigger, creating at least seven Treasure tokens.
4. Resolve the Combat Celebrant trigger, untapping all other creatures you control and causing you to get an additional combat phase after this one.
5. Holding priority, activate Umbral Collar Zealot by sacrificing Combat Celebrant.
6. Activate three Treasures by tapping and sacrificing them, adding 2.
7. Activate Ruthless Technomancer by paying 2 and sacrificing four Treasures, returning Combat Celebrant from your graveyard to the battlefield.
8. Repeat from step 2 each combat phase.

This intricate loop centers around Combat Celebrant, whose exertion grants an extra combat phase and untaps your team, while Luxurious Locomotive provides the fuel by churning out a flood of Treasure tokens every time it attacks, scaled by the creatures that crewed it. To keep the engine running, Umbral Collar Zealot provides a convenient sacrifice outlet to send Combat Celebrant to the graveyard, setting the stage for Ruthless Technomancer to resurrect it using a portion of the accumulated Treasures. By recycling the Celebrant through the graveyard and back to the battlefield via the Technomancer's reanimation ability, you can endlessly repeat the attack steps and generate an unbounded surplus of treasures, mana, and combat phases.