Blightbeetle + Wrong Turn + Bartolomé del Presidio

Blightbeetle

Wrong Turn

Bartolomé del Presidio

How it works

1. Donate Blightbeetle to an opponent
2. Activate Bartolomé del Presidio by sacrificing the undying creature.
3. When the undying creature dies, its undying ability triggers, returning itself from your graveyard to the battlefield without a +1/+1 counter on it due to Blightbeetle.
4. Resolve the Bartolomé del Presidio ability.
5. Repeat from step 2.

This loop uses Wrong Turn to hand your opponent a Blightbeetle, turning their side of the board into a graveyard-recursion engine thanks to its static ability that prevents opponents' creatures from ever receiving +1/+1 counters. With that restriction in place, you can feed any undying creature to Bartolomé del Presidio over and over again; because the counter can never be placed, the creature refuses to stay dead and immediately triggers its own return. Meanwhile, every sacrifice pumps up Bartolomé del Presidio with endless +1/+1 counters, netting you an infinite stream of sacrifices, enters-the-battlefield triggers, and leaves-the-battlefield triggers.