Havengul Lich + Rooftop Storm + Shambling Ghast + Phantom Train

Havengul Lich

Rooftop Storm

Shambling Ghast

Phantom Train

How it works

1. Activate Havengul Lich by paying 1, allowing you to cast Shambling Ghast card from your graveyard this turn.
2. Cast Shambling Ghast from your graveyard by paying 0 due to Rooftop Storm.
3. Activate Phantom Train by sacrificing Shambling Ghast.
4. When Shambling Ghast dies, it triggers, creating a Treasure token.
5. Resolve the Phantom Train ability.
6. Activate the Treasure by tapping and sacrificing it, adding 1.
7. Repeat.

This engine turns an ordinary graveyard into an infinite loop by combining Havengul Lich's ability to cast creatures from the graveyard with Rooftop Storm, which reduces the mana cost of those Zombie spells to zero. Shambling Ghast is the crucial sacrifice fodder that feeds Phantom Train, and every time the Ghast dies to the Train's activation, its own death trigger steps in to replace your spent mana by creating a Treasure token. By sacrificing that Treasure for {1}, you fund the Lich's activation fee to repeat the whole cycle, continuously growing Phantom Train with infinite +1/+1 counters while generating an endless storm of artifact and creature triggers.