Blightbeetle + Altar of Dementia + Wrong Turn

Blightbeetle

Altar of Dementia

Wrong Turn

How it works

1. Donate Blightbeetle to an opponent
2. Activate Altar of Dementia 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 Altar of Dementia ability.
5. Repeat from step 2.

By orchestrating a clever exchange with Wrong Turn, you hand your opponent control of Blightbeetle, locking down their board so that creatures can never receive +1/+1 counters. With that static prevention active, any creature with undying that you sacrifice to Altar of Dementia will continually return to the battlefield without the counter that would normally shut the loop down. This lets you endlessly recycle your creature into Altar of Dementia to mill your opponents out completely while generating an infinite storm of sacrifices, leaves-the-battlefield, and death triggers.