Blightbeetle + Umbral Collar Zealot + Coveted Falcon

Blightbeetle

Umbral Collar Zealot

Coveted Falcon

How it works

1. Activate Coveted Falcon by paying 1, turning it face up.
2. Coveted Falcon triggers, causing an opponent to gain control of Blightbeetle and causing you to draw a card.
3. Activate Umbral Collar Zealot by sacrificing the undying creature.
4. 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.
5. Resolve the Umbral Collar Zealot ability.
6. Repeat from step 3.

This clever loop turns an undying creature into a perpetual motion machine by using Blightbeetle's passive ability to suppress the +1/+1 counters that would normally lock your creatures out of returning permanently. You fuel the engine with Umbral Collar Zealot, sacrificing your creature to churn through your library with infinite surveil triggers while repeatedly triggering its death and return cycles. Meanwhile, Coveted Falcon acts as a master of disguise in your deck, though the core of this particular execution relies on the tireless synergy between your sacrifice outlet, your recurring threat, and the beetle that keeps the cycle endlessly open.