Prototype Portal + Dross Scorpion + Myr Moonvessel + Arcbound Ravager

Prototype Portal

Dross Scorpion

Myr Moonvessel

Arcbound Ravager

How it works

1. Activate Prototype Portal by paying 1 and tapping it, creating a token copy of Myr Moonvessel.
2. Activate Arcbound Ravager by sacrificing Myr Moonvessel.
3. When Myr Moonvessel dies, Myr Moonvessel and Dross Scorpion trigger.
4. Resolve the Myr Moonvessel trigger, adding C.
5. Resolve the Dross Scorpion trigger, untapping Prototype Portal.
6. Resolve the Arcbound Ravager ability, putting a +1/+1 counter on it.
7. Repeat.