Saffi Eriksdotter + Eternal Witness + Aluren + Altar of Dementia

Saffi Eriksdotter

Eternal Witness

Aluren

Altar of Dementia

How it works

1. Activate Saffi by sacrificing it, targeting Eternal Witness.
2. Activate Altar of Dementia by sacrificing Eternal Witness.
3. When Eternal Witness dies, Saffi triggers, returning it from your graveyard to the battlefield.
4. When Eternal Witness enters the battlefield, it triggers, returning Saffi from your graveyard to your hand.
5. Resolve the Altar of Dementia ability from step 2, causing target player to mill cards equal to Eternal Witness's power.
6. Cast Saffi by paying 0 due to Aluren.
7. Repeat.