Mortuary + Stonecoil Serpent + Harvester of Souls

Mortuary

Stonecoil Serpent

Harvester of Souls

How it works

1. Cast Stonecoil Serpent by paying 0.
2. Stonecoil Serpent enters and dies as a state-based action due to having 0 toughness, triggering Mortuary and Harvester of Souls.
3. Resolve the Mortuary trigger, putting Stonecoil Serpent from your graveyard onto the top of your library.
4. Resolve the Harvester of Souls trigger, causing you to draw a card, thus drawing Stonecoil Serpent from your library.
5. Repeat.

This elegant loop relies on casting Stonecoil Serpent for zero mana, allowing state-based actions to immediately send it to the graveyard. That death triggers Mortuary, whose replacement effect ensures the Serpent immediately returns to the top of your library instead of lingering in the graveyard. Simultaneously, Harvester of Souls watches for that creature's demise to reward you with a card, drawing the Serpent right back to your hand so you can cast it all over again.