Captain Storm, Cosmium Raider + Lesser Masticore + Leyline of Transformation + Phantom Train

Captain Storm, Cosmium Raider

Lesser Masticore

Leyline of Transformation

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.

By anchoring your creature types around Pirate with Leyline of Transformation, you ensure that every entering artifact or creature immediately fires off Captain Storm, Cosmium Raider's growth trigger. That synergy feeds directly into the engine, where Phantom Train uses Lesser Masticore as a recurring sacrifice fodder to continually add +1/+1 counters to itself. Because Lesser Masticore features persist, its death immediately returns it with a -1/+1 counter, which is then swiftly neutralized by the positive counter from Captain Storm, Cosmium Raider to keep the loop infinitely repeatable.