Priest of Gix + Containment Construct + Dream Halls + Cloudstone Curio + Teferi, Mage of Zhalfir

Priest of Gix

Containment Construct

Dream Halls

Cloudstone Curio

Teferi, Mage of Zhalfir

How it works

1. Cast Priest of Gix by discarding another nonartifact black creature card with mana value two or less.
2. Containment Construct triggers, causing you to exile the discarded card from your graveyard and allowing you to cast it this turn.
3. Priest of Gix enters the battlefield, triggering itself and Cloudstone Curio.
4. Resolve the Priest of Gix trigger, adding .
5. Holding priority, cast the black creature from exile by paying its mana cost.
6. The creature enters the battlefield, triggering Cloudstone Curio, returning Priest of Gix from the battlefield to your hand.
7. Resolve the Cloudstone Curio trigger from step 3, returning the black creature to your hand.
8. Repeat.