Mortuary + Endless One + Gwenom, Remorseless

Mortuary

Endless One

Gwenom, Remorseless

How it works

1. Cast Endless One either from your hand by paying 0 or from the top of your library by paying 0 life.
2. Endless One enters and dies as a state-based action due to having 0 toughness.
3. Mortuary triggers, putting Endless One from your graveyard onto the top of your library.
4. Repeat.

This clever loop turns the zero-cost polymorph of Endless One into a relentless engine by leveraging Mortuary's mandatory replacement effect to recycle the creature straight back to the top of your library each time it perishes from having zero toughness. Normally you'd need a way to cast it from up top, but Gwenom, Remorseless provides the crucial bridge; her attack trigger lets you look at and play cards from your library while generously bypassing mana costs by having you pay life instead. Because Endless One costs zero mana, paying zero life means you can recast it infinitely for a bottomless stream of creature ETB and LTB triggers, stacking up an unstoppable storm count along the way.