Mortuary + Gray Merchant of Asphodel + Phantom Train + Gwenom, Remorseless

Mortuary

Gray Merchant of Asphodel

Phantom Train

Gwenom, Remorseless

How it works

1. Cast Gray Merchant either from your hand by paying 3 or from the top of your library by paying 5 life.
2. When Gray Merchant enters, it triggers, causing each opponent to lose life equal to your devotion to black and causing you to gain life equal to the life lost this way.
3. Activate Phantom Train by sacrificing Gray Merchant.
4. When Gray Merchant dies, Mortuary triggers, putting Gray Merchant from your graveyard onto the top of your library.
5. Resolve the Phantom Train ability.
6. Repeat.

This loop relies on recycling Gray Merchant of Asphodel in and out of the graveyard to endlessly drain your opponents and keep your life total safe. Gwenom, Remorseless is the engine that lets you cheat Gray Merchant straight off the top of your library for life instead of mana, while Mortuary ensures that whenever Gray Merchant dies, it goes right back to the top of your library to be played again. Finally, Phantom Train acts as the necessary sacrifice outlet, letting you feed away Gray Merchant to grow itself while keeping the entire endless cycle moving forward.