Blightbeetle + Blasting Station + Harmless Offering

Blightbeetle

Blasting Station

Harmless Offering

How it works

1. Donate Blightbeetle to an opponent
2. Activate Blasting Station by tapping it and 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. When the undying creature enters, Blasting Station triggers, untapping Blasting Station.
5. Resolve the Blasting Station ability from step 2.
6. Repeat from step 2.

By using Harmless Offering to hand over Blightbeetle to your opponent, you completely lock them out of ever letting their creatures accumulate +1/+1 counters. This passive shutdown is the absolute heart of the engine, allowing you to feed any creature with undying over and over into Blasting Station. Because Blightbeetle prevents those counters from sticking, the undying creature triggers endlessly every time it hits the graveyard, while Blasting Station untaps upon each fresh entry to continuously blast away your opponent's life total.