Mortuary + Atog + Bolas's Citadel + Shield Sphere

Mortuary

Atog

Bolas's Citadel

Shield Sphere

How it works

1. Activate Atog by sacrificing Shield Sphere
2. When Shield Sphere dies, Mortuary triggers, putting Shield Sphere from your graveyard onto the top of your library.
3. Resolve the Atog ability.
4. Cast Shield Sphere from the top of your library by paying 0 life.
5. Repeat.

This loop turns Atog into a bottomless pit of power by leveraging the zero-mana cost of Shield Sphere to continuously churn your library. As you sacrifice Shield Sphere to pump Atog, Mortuary immediately catches it on its way to the graveyard and places it right back onto the top of your library. From there, Bolas's Citadel allows you to play the Shield Sphere again for zero life, feeding the entire engine in a closed loop that generates infinite death triggers, storm count, and a catastrophically huge Atog.