Mortuary + Fleshtaker + Bolas's Citadel + Phyrexian Dreadnought

Mortuary

Fleshtaker

Bolas's Citadel

Phyrexian Dreadnought

How it works

1. Cast Phyrexian Dreadnought from the top of your library by paying 1 life.
2. When Phyrexian Dreadnought enters, it triggers, causing you to sacrifice it.
3. When Phyrexian Dreadnought dies, Mortuary and Fleshtaker trigger.
4. Resolve the Mortuary trigger, putting Phyrexian Dreadnought from your graveyard onto the top of your library.
5. Resolve the Fleshtaker trigger, causing you to gain 1 life and scry 1
6. Repeat.

This clever loop lets you recast Phyrexian Dreadnought directly from the top of your library for a mere 1 life apiece, thanks to Bolas's Citadel allowing you to bypass mana costs with your life total. Whenever the Dreadnought hits the graveyard, Mortuary intercepts it to slide it right back onto the top of your library, ensuring you never run out of ammo. Meanwhile, Fleshtaker puts that sacrifice to work by converting each cycle into a steady stream of life gain and scrys, insulating you from the Citadel's life payments while keeping your topdeck primed for endless repetition.