Nim Deathmantle + Ashnod's Altar + Headless Rider

Nim Deathmantle

Ashnod's Altar

Headless Rider

How it works

1. Activate Ashnod's Altar by sacrificing Headless Rider, adding CC.
2. When Headless Rider dies, it and Nim Deathmantle trigger,
3. Resolve the Headless Rider trigger, creating a creature token.
4. Holding priority, activate Ashnod's Altar by sacrificing a creature token, adding CC.
5. Resolve the Nim Deathmantle trigger, causing you to pay 4 to return Headless Rider from your graveyard to the battlefield and attach Nim Deathmantle to it.
6. Repeat.