Szarel, Genesis Shepherd + Crystalline Crawler + Umbral Collar Zealot + Oathsworn Vampire

Szarel, Genesis Shepherd

Crystalline Crawler

Umbral Collar Zealot

Oathsworn Vampire

How it works

1. Cast Oathsworn Vampire from your graveyard by paying its mana cost.
2. Activate Umbral Collar Zealot by sacrificing Oathsworn Vampire.
3. When Oathsworn Vampire is sacrificed, Szarel triggers, putting a number of +1/+1 counters equal to Szarel's power on Crystalline Crawler.
4. Resolve the Umbral Collar Zealot ability.
5. Activate Crystalline Crawler twice by removing two +1/+1 counters from it, adding 1.
6. Repeat.

This ingenious loop lets you turn life gain and sacrifices into an unstoppable engine of growth and mana. You begin by casting Oathsworn Vampire directly from your graveyard, fueled by the fact that you gained life this turn. From there, Umbral Collar Zealot acts as the perfect sacrifice outlet, feeding the vampire to its ability while triggering Szarel, Genesis Shepherd, which pumps Crystalline Crawler with a massive influx of +1/+1 counters based on Szarel's power. Finally, Crystalline Crawler converts those newly acquired counters right back into the colored mana you need to pay for the vampire's return, leaving you with infinite sacrifices, storm count, and surveils to sculpt your victory.