Fain, the Broker + Thornbite Staff + Pitiless Plunderer + Spawning Pit

Fain, the Broker

Thornbite Staff

Pitiless Plunderer

Spawning Pit

How it works

1. Activate Fain's third ability by tapping it and sacrificing another artifact, creating a 2/1 Inkling creature token.
2. Activate Spawning Pit by sacrificing the Inkling.
3. When the Inkling dies, Fain and Pitiless Plunderer trigger.
4. Resolve the Fain trigger, untapping it.
5. Resolve the Pitiless Plunderer trigger, creating a Treasure token.
6. Resolve the Spawning Pit ability
7. Repeat.