Cauldron of Souls + Dross Scorpion + Arsenal Thresher + Sarcatog

Cauldron of Souls

Dross Scorpion

Arsenal Thresher

Sarcatog

How it works

1. Activate Cauldron of Souls by tapping it, giving Arsenal Thresher persist until end of turn.
2. Activate Sarcatog's second ability by sacrificing Arsenal Thresher.
3. When Arsenal Thresher dies, its persist ability and Dross Scorpion trigger.
4. Resolve the Dross Scorpion trigger, untapping Cauldron of Souls.
5. Resolve the Arsenal Thresher trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it, and then choosing to reveal at least one artifact card from your hand to remove the -1/-1 counter.
6. Resolve the Sarcatog ability, giving it +1/+1 until end of turn.
7. Repeat.

This intricate loop transforms a quiet graveyard into an engine of endless rebirth, centered around Cauldron of Souls granting persist to Arsenal Thresher. When Sarcatog steps in to sacrifice the Thresher, it simultaneously triggers its own growth while sending the artifact creature to the graveyard, which in turn triggers Dross Scorpion to neatly untap the Cauldron for the next iteration. Because Arsenal Thresher checks for revealed artifacts from your hand as it enters, it conveniently cancels out its own new -1/-1 counter right on the spot.