Cauldron of Souls + Dross Scorpion + Arsenal Thresher + Bartolomé del Presidio

Cauldron of Souls

Dross Scorpion

Arsenal Thresher

Bartolomé del Presidio

How it works

1. Activate Cauldron of Souls by tapping it, giving Arsenal Thresher persist until end of turn.
2. Activate Bartolomé del Presidio 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 Bartolomé del Presidio ability, putting a +1/+1 counter on it.
7. Repeat.

This clever loop turns Arsenal Thresher into an immortal engine by leveraging Cauldron of Souls to grant it persist, allowing Bartolomé del Presidio to repeatedly sacrifice it for value. Every time the Thresher hits the graveyard, Dross Scorpion triggers off its artifact nature to untap the Cauldron, keeping the bestowal of persist rolling. The true brilliance of the loop lies in Arsenal Thresher's own entry ability: by revealing an artifact from your hand as it returns with a -1/-1 counter, you can place a +1/+1 counter on it, which immediately neutralizes the -1/-1 counter through state-based actions.