Triskelavus + Vigor + Mana Echoes

Triskelavus

Vigor

Mana Echoes

How it works

1. Activate Triskelavus by paying 1 and removing a +1/+1 counter from it, creating a 1/1 Triskelavite artifact creature token.
2. The Triskelavite enters the battlefield, triggering Mana Echoes, adding C for each Triskelavite you control.
3. Activate a Triskelavite by sacrificing it, targeting Triskelavus.
4. The damage that would be dealt to Triskelavus is prevented by Vigor, putting a +1/+1 counter on Triskelavus.
5. Repeat.