Basri's Lieutenant + Grumgully, the Generous + Altar of Dementia

Basri's Lieutenant

Grumgully, the Generous

Altar of Dementia

How it works

1. Activate Altar of Dementia by sacrificing a creature with at least one +1/+1 counter.
2. Basri's Lieutenant trigger, creating a 2/2 Knight token.
3. When Knight token enters the battlefield, Grumgully triggers, putting a +1/+1 counter on Knight token.
4. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power.
5. Repeat.

This loop turns an infinite cycle of sacrifices and resurrections into total library destruction, powered by Altar of Dementia to mill your opponent out card by card. The engine relies on Grumgully, the Generous to ensure that every newly minted Knight token enters the battlefield with a fresh +1/+1 counter already placed upon it. Because of that crucial counter, sacrificing the token to Altar of Dementia triggers Basri's Lieutenant, which both replaces the fallen warrior with a brand-new 2/2 Knight token and keeps the unbroken chain of triggers rolling indefinitely.