Saffi Eriksdotter + Reveillark + Altar of Dementia

Saffi Eriksdotter

Reveillark

Altar of Dementia

How it works

1. Activate Saffi by sacrificing it, targeting Reveillark.
2. Activate Altar of Dementia by sacrificing Reveillark.
3. When Reveillark dies, it and Saffi trigger.
4. Resolve the Saffi trigger, returning Reveillark from your graveyard to the battlefield.
5. Resolve the Reveillark trigger, returning Saffi from your graveyard to the battlefield.
6. Resolve the Altar of Dementia ability from step 2, causing target player to mill cards equal to Reveillark's power.
7. Repeat.