Enduring Renewal + Crystalline Crawler + Sunbond + Ravenous Baloth

Enduring Renewal

Crystalline Crawler

Sunbond

Ravenous Baloth

How it works

1. Activate Ravenous Baloth by sacrificing it.
2. When Ravenous Baloth dies, Enduring Renewal triggers, returning Ravenous Baloth to your hand from your graveyard.
3. Resolve the Ravenous Baloth ability, causing you to gain 4 life.
4. Crystalline Crawler triggers, putting four +1/+1 counters on itself.
5. Activate Crystalline Crawler's first ability four times by removing four +1/+1 counters from it, adding 2.
6. Cast Ravenous Baloth by paying 2.
7. Repeat.
8. If you control another nontoken Beast with mana value 3 or less, you may instead sacrifice it to get infinite mana and +1/+1 counters on Crystalline Crawler.

This clever loop turns the cycle of life and death into a perpetual motion machine by anchoring itself around Enduring Renewal's replacement and graveyard-return effects. When you sacrifice Ravenous Baloth to its own activated ability, Enduring Renewal instantly catches it on the way to the graveyard and bounces it right back to your hand. Meanwhile, the life you gain from that sacrifice feeds Sunbond, which is enchanted to Crystalline Crawler and triggers to pile +1/+1 counters onto it. You can then cash in those newly minted counters using Crystalline Crawler's mana ability to fund recasting Ravenous Baloth, keeping the entire engine running indefinitely.