Prototype Portal + Dross Scorpion + Carrion Feeder + Cathodion

Prototype Portal

Dross Scorpion

Carrion Feeder

Cathodion

How it works

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