Nim Deathmantle + Ashnod's Altar + Thopter Mechanic

Nim Deathmantle

Ashnod's Altar

Thopter Mechanic

How it works

1. Activate Ashnod's Altar by sacrificing Thopter Mechanic, adding CC.
2. Thopter Mechanic dies, triggering itself and Nim Deathmantle.
3. Resolve the Thopter Mechanic trigger, creating a 1/1 Thopter artifact creature token.
4. Activate Ashnod's Altar by sacrificing the Thopter, adding CC.
5. Resolve the Nim Deathmantle trigger from step 2, causing you to pay 4 to return Thopter Mechanic from your graveyard to the battlefield, and attach Nim Deathmantle to it.
6. Repeat.