Eternal Scourge + Young Deathclaws + Crystalline Crawler + Umbral Collar Zealot + The Earth Crystal

Eternal Scourge

Young Deathclaws

Crystalline Crawler

Umbral Collar Zealot

The Earth Crystal

How it works

1. Activate Eternal Scourge's scavenge ability, granted to it by Young Deathclaws, by paying 3 and exiling Eternal Scourge from your graveyard, putting six +1/+1 counters on Crystalline Crawler due to The Earth Crystal.
2. Activate Crystalline Crawler six times by removing six +1/+1 counters from it, adding 6.
3. Cast Eternal Scourge from exile by paying 3.
4. Activate Umbral Collar Zealot by sacrificing Eternal Scourge.
5. Repeat.

This intricate loop turns a creature that simply refuses to stay dead into an engine for infinite sacrifices and surveils. The magic begins because Young Deathclaws grants every creature card in your graveyard scavenge equal to its mana cost, allowing you to continually exile Eternal Scourge to pump up Crystalline Crawler. While you are doing this, The Earth Crystal doubles every +1/+1 counter placed on Crystalline Crawler, ensuring that its counters yield more mana than you spent on the scavenge cost. Once Crystalline Crawler converts those counters into a surplus of mana, you recast Eternal Scourge directly from exile and sacrifice it to Umbral Collar Zealot to trigger its surveil ability, sending the Scourge straight back to the graveyard to do it all over again.