Mortuary + Bolas's Citadel + Shifting Wall

Mortuary

Bolas's Citadel

Shifting Wall

How it works

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

This clever loop turns the zero-cost artifact creature Shifting Wall into an infinite engine by leveraging its X-cost sizing—cast it with X equal to zero, and state-based actions immediately send it to the graveyard. That’s where Mortuary steps in, instantly intercepting the creature to recycle it right back to the top of your library instead of letting it rest. Meanwhile, Bolas's Citadel lets you bypass paying mana entirely, substituting life payments while allowing you to continuously recast Shifting Wall from the top of your library without ever running out of fuel.