Cauldron of Souls + Dross Scorpion + Umbral Collar Zealot + Mycosynth Lattice

Cauldron of Souls

Dross Scorpion

Umbral Collar Zealot

Mycosynth Lattice

How it works

1. Activate Cauldron of Souls by tapping it, giving the creature with bloodthirst persist until end of turn.
2. Activate Umbral Collar Zealot by sacrificing the creature with bloodthirst.
3. When the creature dies, its persist ability and Dross Scorpion trigger.
4. Resolve the persist trigger, returning the creature from your graveyard to the battlefield, which enters the battlefield with at least one +1/+1 counter on it due to its bloodthirst ability.
5. Resolve the Dross Scorpion trigger, untapping Cauldron of Souls.
6. Resolve the Umbral Collar Zealot ability
7. Repeat.

This clever loop transforms a pile of disparate metal and flesh into an endless engine of resurrection, powered entirely by how Mycosynth Lattice turns every permanent on your battlefield into an artifact. That global transformation is what allows Dross Scorpion to spot every death and dutifully untap Cauldron of Souls, which in turn grants persist to whatever creature you feed into Umbral Collar Zealot. Because your sacrificed creature returns with a -1/-1 counter from persist but immediately cancels it out with its own +1/+1 counters from bloodthirst, it can safely die over and over again without ever staying in the graveyard for good.