Dualcaster Mage + Extract from Darkness + Yahenni, Undying Partisan

Dualcaster Mage

Extract from Darkness

Yahenni, Undying Partisan

How it works

1. Cast Extract from Darkness by paying its mana cost
2. Holding priority, cast Dualcaster Mage by paying its mana cost.
3. When Dualcaster Mage enters, it triggers, targeting Extract from Darkness.
4. Holding priority, activate Yahenni by sacrificing Dualcaster Mage.
5. Resolve the Dualcaster Mage trigger, copying Extract from Darkness
6. Resolve the Extract from Darkness copy, causing each player to mill two cards and returning Dualcaster Mage from your graveyard to the battlefield.
7. Repeat from step 3.

This clever loop turns Extract from Darkness into a self-sustaining engine by relying on the recursive threat of Dualcaster Mage. When you cast the sorcery and flash in Dualcaster Mage, its enters-the-battlefield trigger targets the original spell, while Yahenni, Undying Partisan stands ready to sacrifice the Mage to its own activation to keep the graveyard stocked. The copied Extract from Darkness resolves first, milling cards and immediately returning Dualcaster Mage from the graveyard back to the battlefield to repeat the entire process indefinitely.