Nim Deathmantle + Ashnod's Altar + Crawling Chorus

Nim Deathmantle

Ashnod's Altar

Crawling Chorus

How it works

1. Activate Ashnod's Altar by sacrificing Crawling Chorus, adding CC.
2. When Crawling Chorus dies, it and Nim Deathmantle trigger,
3. Resolve the Crawling Chorus 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 Crawling Chorus from your graveyard to the battlefield and attach Nim Deathmantle to it.
6. Repeat.