Nim Deathmantle + Ashnod's Altar + Gutter Grime

Nim Deathmantle

Ashnod's Altar

Gutter Grime

How it works

1. Activate Ashnod's Altar by sacrificing another nontoken creature, adding CC.
2. The creature dies, triggering Nim Deathmantle and Gutter Grime.
3. Resolve the Gutter Grime trigger, putting a slime counter on it and creating an X/X Ooze creature token.
4. Resolve the Nim Deathmantle trigger, causing you to pay 4 to return the nontoken creature from your graveyard to the battlefield, and attach Nim Deathmantle to it.
5. Activate Ashnod's Altar by sacrificing the Ooze, adding CC.
6. Repeat.