Requires

Prosper, Tome-Bound must be on the battlefield. Ugin, the Ineffable must be on the battlefield. Eternal Scourge must be on the battlefield. Planar Void must be on the battlefield. Altar of Dementia must be on the battlefield. Mana needed:

Steps

1. Activate Altar of Dementia by sacrificing Eternal Scourge.
2. Planar Void triggers, exiling Eternal Scourge from your graveyard.
3. Resolve the Altar of Dementia ability, milling target player for an amount equal to Eternal Scourge's power.
4. Cast Eternal Scourge for .
5. Prosper triggers, creating a Treasure token.
6. Resolve Eternal Scourge, allowing it to enter the battlefield.
7. Activate the Treasure token by tapping and sacrificing it, adding one mana of any color.
8. Repeat.

Results