Eternal Scourge + Nightmare Shepherd + Ashnod's Altar

Eternal Scourge

Nightmare Shepherd

Ashnod's Altar

How it works

1. Activate Ashnod's Altar by sacrificing Eternal Scourge, adding CC.
2. Nightmare Shepherd triggers.
3. Resolve the Nightmare Shepherd trigger, exiling Eternal Scourge from your graveyard and creating a 1/1 copy of Eternal Scourge that is a Nightmare in addition to its other types.
4. Activate Ashnod's Altar by sacrificing the Eternal Scourge token, adding CC.
5. Cast Eternal Scourge from exile by paying 3.
6. Repeat.