Captain Storm, Cosmium Raider + Lesser Masticore + Xenograft + Phantom Train

Captain Storm, Cosmium Raider

Lesser Masticore

Xenograft

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Lesser Masticore.
2. When Lesser Masticore dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Lesser Masticore enters the battlefield, Captain Storm triggers, putting a +1/+1 counter on Lesser Masticore.
4. Resolve the Phantom Train ability.
5. Repeat.

This looping machinery relies on Xenograft to turn Lesser Masticore into a Pirate, allowing it to benefit from the continuous influx of counters while feeding the engine. By using Phantom Train to sacrifice Lesser Masticore, its persist ability brings it back with a -1/-1 counter, but the very act of entering triggers Captain Storm, Cosmium Raider to place a +1/+1 counter on it. State-based actions immediately cancel out the -1/+1 and +1/+1 counters, resetting the Masticore so it can be sacrificed to the Phantom Train all over again.