Prototype Portal + Clock of Omens + Battered Golem + Great Furnace

Prototype Portal

Clock of Omens

Battered Golem

Great Furnace

How it works

1. Activate Prototype Portal by paying 0, creating a token copy of Great Furnace.
2. When the Great Furnace token enters the battlefield, Battered Golem triggers, untapping itself.
3. Activate Clock of Omens by tapping Battered Golem and the Great Furnace token, untapping Prototype Portal.
4. Repeat.

This engine turns the ability to replicate artifacts into an unstoppable loop by using Clock of Omens to constantly untap Prototype Portal. The secret to sustaining this cycle is Battered Golem, whose static ability sees each new artifact token enter the battlefield and untaps itself as a result. By pairing the Golem with a copy of Great Furnace imprinted on the Portal and fed by zero-mana activations, you have two tapped artifacts ready to fuel the Clock of Omens and reset the whole process indefinitely.