Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Geralf's Mindcrusher + Altar of Dementia

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Geralf's Mindcrusher

Altar of Dementia

How it works

1. Activate Altar of Dementia by sacrificing Geralf's Mindcrusher
2. When Geralf's Mindcrusher dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. When Geralf's Mindcrusher enters, it triggers, causing a player to mill five cards.
4. Activate Altar of Dementia by sacrificing Geralf's Mindcrusher
5. When Geralf's Mindcrusher dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
6. When Geralf's Mindcrusher enters, it triggers, causing a player to mill five cards.
7. Resolve both Altar of Dementia abilities from step 1 and 4.
8. Repeat.

This loop relies on toggling the front and back faces of Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight to endlessly recycle Geralf's Mindcrusher. While Eirdu grants your creature spells convoke, its transformed night-side, Isilu, Carrier of Twilight, blesses your other nontoken creatures with persist, setting up an eternal recursion when paired with the undying already native to Geralf's Mindcrusher. By repeatedly sacrificing Geralf's Mindcrusher to Altar of Dementia, you alternately place +1/+1 and -1/+1 counters on it that seamlessly cancel each other out upon each return to the battlefield. Every iteration triggers Geralf's Mindcrusher's entry ability to mill cards while Altar of Dementia mills your target player into oblivion.