Blightbeetle + Blim, Comedic Genius + Yahenni, Undying Partisan

Blightbeetle

Blim, Comedic Genius

Yahenni, Undying Partisan

How it works

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

By using Blim, Comedic Genius to generously donate a Blightbeetle to your opponent, you completely invert the rules of engagement, turning your opponent's side of the board into a sterile environment where +1/+1 counters simply cannot exist. This cleverly neuters any "undying" or similar mechanics that rely on placing counters, which is precisely what allows an unspecified undying creature to loop endlessly when combined with Yahenni, Undying Partisan. As you sacrifice that creature to fuel Yahenni, Undying Partisan's sacrificial appetite and pump its power, the creature’s own recursion trigger brings it right back to the battlefield—completely free of the counters that would normally stop the cycle, thanks to the very Blightbeetle your opponent now controls.