Scarecrone + Thornbite Staff + Cathodion + Phyrexian Altar

Scarecrone

Thornbite Staff

Cathodion

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing Cathodion, adding 1.
2. Cathodion dies, triggering itself and Scarecrone.
3. Resolve the Cathodion trigger, adding CCC.
4. Resolve the Scarecrone trigger, untapping it.
5. Activate Scarecrone's second ability by paying 4 and tapping it, returning Cathodion from your graveyard to the battlefield.
6. Repeat.