Mortuary + Harvester of Souls + Hangarback Walker

Mortuary

Harvester of Souls

Hangarback Walker

How it works

1. Cast Hangarback Walker by paying 0.
2. Hangarback Walker 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 Hangarback Walker from your graveyard onto the top of your library.
4. Resolve the Harvester of Souls trigger, causing you to draw a card, thus drawing Hangarback Walker from your library.
5. Repeat.

This clever loop turns the zero-mana casting cost of Hangarback Walker into a perpetual motion machine of card draw and triggers. As soon as the Walker hits the battlefield, state-based actions send it straight to the graveyard, where Mortuary immediately catches it and neatly places it back on top of your library. Meanwhile, Harvester of Souls watches the creature die and rewards you by drawing that very same card right back into your hand. By repeating this process, you can churn through your entire deck while generating infinite artifact deaths and leave-the-battlefield triggers.