Blightbeetle + Phyrexian Altar + Zedruu the Greathearted

Blightbeetle

Phyrexian Altar

Zedruu the Greathearted

How it works

1. Donate Blightbeetle to an opponent
2. Activate Phyrexian Altar 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. Repeat from step 2.

This clever loop relies on Zedruu the Greathearted and her ability to donate permanents to your opponents, turning a specific defensive asset into a hostile trap. By gifting Blightbeetle to someone else, its static ability prevents their creatures from ever receiving +1/+1 counters, which sabotages any standard mechanics that rely on them. Meanwhile, Phyrexian Altar acts as the engine, turning your own creatures into a continuous stream of colored mana and death triggers while bypassing the usual counter-based limitations of undying-style loops.