Basri's Lieutenant + Securitron Squadron + Altar of Dementia

Basri's Lieutenant

Securitron Squadron

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 triggers, creating a 2/2 Knight creature token.
3. When the Knight token enters the battlefield, Securitron Squadron triggers, putting a +1/+1 counter on the Knight.
4. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power.
5. Repeat.