Eternal Scourge + Young Deathclaws + Crystalline Crawler + Phyrexian Altar + Primal Vigor

Eternal Scourge

Young Deathclaws

Crystalline Crawler

Phyrexian Altar

Primal Vigor

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 Primal Vigor.
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 Phyrexian Altar by sacrificing Eternal Scourge.
5. Repeat.

This loop turns a clever graveyard interaction into an infinite engine by using Young Deathclaws to grant Eternal Scourge its scavenge ability from the graveyard, allowing you to pay its mana cost and exile it to target Crystalline Crawler. Because Primal Vigor doubles the number of +1/+1 counters placed on Crystalline Crawler, the scavenge nets you a surplus of counters that you can immediately turn into colored mana by removing them. You then recast Eternal Scourge directly from exile and feed it to Phyrexian Altar to generate even more mana, resetting the loop so you can repeat the process infinitely.