Blightbeetle + Wrong Turn + Bloodflow Connoisseur

Blightbeetle

Wrong Turn

Bloodflow Connoisseur

How it works

1. Donate Blightbeetle to an opponent
2. Activate Bloodflow Connoisseur 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 Bloodflow Connoisseur ability.
5. Repeat from step 2.

This clever loop uses Wrong Turn to gift a Blightbeetle to your opponent, turning their side of the board into a counter-prevention zone where no +1/+1 counters can ever land. With that restriction in place, you can feed creatures to Bloodflow Connoisseur over and over; whenever an undying creature hits the graveyard, Blightbeetle's passive effect stops it from returning with the counter that would normally lock it out of the loop. This lets you sacrifice the same creature indefinitely, generating infinite leaves-the-battlefield, enters-the-battlefield, death, and sacrifice triggers while continuously growing your Bloodflow Connoisseur.