Mortuary + Hangarback Walker + Gwenom, Remorseless

Mortuary

Hangarback Walker

Gwenom, Remorseless

How it works

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

This clever loop turns Hangarback Walker into a zero-mana engine by exploiting its zero toughness when cast with X equal to zero, immediately sending it to the graveyard where Mortuary dutifully redirects it straight back to the top of your library. Gwenom, Remorseless ties the whole operation together: as long as Gwenom has attacked that turn, her ability lets you bypass mana costs to recast the Walker directly from the top of your library by paying life instead, seamlessly feeding the loop again and again.