Koll, the Forgemaster + Demonmail Hauberk + Umbral Mantle + Cathodion

Koll, the Forgemaster

Demonmail Hauberk

Umbral Mantle

Cathodion

How it works

1. Activate Umbral Mantle's equip ability by paying 0, attaching it to Cathodion.
2. Activate Demonmail Hauberk by sacrificing Cathodion, targeting Koll.
3. When Cathodion dies, it and Koll trigger.
4. Resolve the Cathodion trigger, adding CCC.
5. Resolve the Koll trigger, returning it from your graveyard to your hand.
6. Resolve the Demonmail Hauberk ability, attaching it to Koll.
7. Cast Cathodion by paying its mana cost.
8. Repeat.