Cauldron of Souls + Corridor Monitor + Cathars' Crusade + Goblin Bombardment

Cauldron of Souls

Corridor Monitor

Cathars' Crusade

Goblin Bombardment

How it works

1. Activate Cauldron of Souls by tapping it, giving Corridor Monitor persist until end of turn.
2. Activate Goblin Bombardment by sacrificing Corridor Monitor.
3. When Corridor Monitor dies, its persist ability triggers, returning itself from your graveyard to the battlefield with a -1/-1 counter on it.
4. When Corridor Monitor enters the battlefield, it and Cathars' Crusade trigger.
5. Resolve the Corridor Monitor trigger, untapping Cauldron of Souls.
6. Resolve the Cathars' Crusade trigger, putting a +1/+1 counter on each creature you control.
7. Resolve the Goblin Bombardment ability from step 2, dealing 1 damage to any target.
8. Repeat.

This clever loop turns a modest automaton into an endless engine of destruction by playing a game of give-and-take with counters. Cauldron of Souls grants persist to Corridor Monitor, letting it cheat death once, while Goblin Bombardment provides the necessary sacrifice outlet to send it to the graveyard in the first place. When the Monitor returns with a debilitating -1/-1 counter, its entry triggers Cathars' Crusade, whose powerful static-driven growth drops a +1/+1 counter on every creature you control; this instantly neutralizes the -1/-1 counter through the rules of state-based actions. At the same time, the Monitor's own entrance untaps Cauldron of Souls via its triggered ability, resetting the artifact so the entire sequence can loop indefinitely for infinite damage and monumental growth.