Mortuary + Gray Merchant of Asphodel + Thermopod + Gwenom, Remorseless

Mortuary

Gray Merchant of Asphodel

Thermopod

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 Thermopod by sacrificing Gray Merchant.
4. When Gray Merchant dies, Mortuary triggers, putting Gray Merchant from your graveyard onto the top of your library.
5. Repeat.

This ingenious loop turns your devotion to black into an unstoppable engine of life-drain and red mana. By using Thermopod to sacrifice Gray Merchant of Asphodel as it enters, you trigger Mortuary to immediately recycle the Merchant back onto the top of your library. From there, Gwenom, Remorseless lets you bypass traditional mana costs by casting the Gray Merchant directly off the top of your library for a mere 5 life—a cost easily offset by the massive life-swing generated by the Merchant's own entry trigger.