Prototype Portal + Dross Scorpion + Shilgengar, Sire of Famine + Cathodion

Prototype Portal

Dross Scorpion

Shilgengar, Sire of Famine

Cathodion

How it works

1. Activate Prototype Portal by paying 3 and tapping it, creating a token copy of Cathodion.
2. Activate Shilgengar 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 Shilgengar ability, creating a Blood token.
7. Repeat.