Mortuary + Gray Merchant of Asphodel + Altar of Dementia + Gwenom, Remorseless

Mortuary

Gray Merchant of Asphodel

Altar of Dementia

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 Altar of Dementia 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 Altar of Dementia ability.
6. Repeat.

This loop turns an infinite recycling engine into a game-winning drain by leveraging Mortuary's triggered ability to instantly intercept Gray Merchant of Asphodel as it dies and place it right back on top of your library. From there, Gwenom, Remorseless grants you the crucial ability to play cards directly from the top of your library while bypassing its mana cost with life payments, allowing you to continually cast the Merchant using the life it drains from your opponents. To keep the cycle moving, Altar of Dementia provides the necessary sacrifice outlet to bin the Merchant on demand while simultaneously milling away your opponents' libraries.