Nim Deathmantle + Ashnod's Altar + Rekindling Phoenix

Nim Deathmantle

Ashnod's Altar

Rekindling Phoenix

How it works

1. Activate Ashnod's Altar by sacrificing Rekindling Phoenix, adding CC.
2. When Rekindling Phoenix dies, it and Nim Deathmantle triggers.
3. Resolve the Rekindling Phoenix trigger, creating a 0/1 Elemental creature token.
4. Activate Ashnod's Altar by sacrificing the Elemental, adding CC.
5. Resolve the Nim Deathmantle trigger from step 2, causing you to pay 4 to return Rekindling Phoenix from your graveyard to the battlefield, and attach Nim Deathmantle to it.
6. Repeat.