Shepherd of the Cosmos + Kaya's Ghostform + Altar of Dementia

Shepherd of the Cosmos

Kaya's Ghostform

Altar of Dementia

How it works

1. Activate Altar of Dementia by sacrificing Shepherd of the Cosmos.
2. When Shepherd of the Cosmos dies, Kaya's Ghostform triggers, returning Shepherd of the Cosmos from your graveyard to the battlefield.
3. When Shepherd of the Cosmos enters the battlefield, it triggers, returning Kaya's Ghostform from your graveyard to the battlefield attached to Shepherd of the Cosmos.
4. Resolve the Altar of Dementia ability, causing target player to mill cards equal to Shepherd of the Cosmos' power.
5. Repeat.

This clever loop transforms a humble recursion engine into a total demolition of your opponent's library. You begin by sacrificing Shepherd of the Cosmos to Altar of Dementia, which feeds the mill engine using the creature's own power. As the Shepherd hits the graveyard, Kaya's Ghostform immediately swoops in to trigger its return to the battlefield. Because the Shepherd's enter-the-battlefield ability targets any permanent with mana value 2 or less, it conveniently plucks Kaya's Ghostform right back out of the graveyard and reattaches it to itself, leaving the entire setup ready to repeat indefinitely.