Metalwork Colossus + Pitiless Plunderer + Sly Requisitioner + Krark-Clan Ironworks

Metalwork Colossus

Pitiless Plunderer

Sly Requisitioner

Krark-Clan Ironworks

How it works

1. Activate Krark-Clan Ironworks by sacrificing Metalwork Colossus, adding CC.
2. When Metlwork Colossus dies, Sly Requisitioner and Pitiless Plunderer trigger.
3. Resolve the Sly Requisitioner trigger, creating a 1/1 Servo artifact creature token.
4. Resolve the Pitiless Plunderer trigger, creating a Treasure artifact token.
5. Activate Metalwork Colossus by sacrificing the Servo and the Treasure token, returning Metalwork Colossus from your graveyard to your hand.
6. Cast Metalwork Colossus by paying at most 1.
7. Repeat.