Mortuary + Bolas's Citadel + Bartolomé del Presidio + Shield Sphere

Mortuary

Bolas's Citadel

Bartolomé del Presidio

Shield Sphere

How it works

1. Activate Bartolomé del Presidio 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 Bartolomé del Presidio ability.
4. Cast Shield Sphere from the top of your library by paying 0 life.
5. Repeat.

This clever loop turns the zero-mana artifact Shield Sphere into an infinite engine by leveraging Mortuary's triggered ability to instantly recycle the sphere back to the top of your library every time it hits the graveyard. Bolas's Citadel makes that recycling effortless by granting you the ability to peer into the future and cast the Shield Sphere directly from the top of your library for zero life. Meanwhile, Bartolomé del Presidio acts as the willing executioner, providing the sacrifice outlet needed to start the loop and growing larger with endless +1/+1 counters for your trouble.