Szarel, Genesis Shepherd + Crystalline Crawler + Gravecrawler + Phantom Train

Szarel, Genesis Shepherd

Crystalline Crawler

Gravecrawler

Phantom Train

How it works

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

This elegant graveyard loop harnesses Gravecrawler's ability to repeatedly cast itself from the graveyard as long as you control another Zombie. Phantom Train provides the necessary sacrifice outlet, and its ability conveniently transforms it into a Spirit artifact creature—keeping Gravecrawler's casting condition satisfied at all times. Meanwhile, Szarel, Genesis Shepherd watches over your sacrifices, converting each one into a massive burst of +1/+1 counters distributed directly onto Crystalline Crawler, whose counters can then be peeled away for mana to fuel the loop indefinitely.