Mortuary + Carmen, Cruel Skymarcher + Bolas's Citadel + Myr Scrapling

Mortuary

Carmen, Cruel Skymarcher

Bolas's Citadel

Myr Scrapling

How it works

1. Activate Myr Scrapling by sacrificing it.
2. When Myr Scrapling dies, Mortuary and Carmen trigger.
3. Resolve the Mortuary trigger, putting Myr Scrapling from your graveyard onto the top of your library.
4. Resolve the Carmen trigger, causing you to gain 1 life and put a +1/+1 counter on Carmen.
5. Resolve the Myr Scrapling ability.
6. Cast Myr Scrapling from the top of your library by paying 1 life.
7. Repeat.

This clever loop spins entirely around the sacrifice of Myr Scrapling, which triggers Mortuary to seamlessly place the tiny robot back on top of your library instead of letting it rest in peace. Meanwhile, Carmen, Cruel Skymarcher happily grows larger and pads your life total with every sacrifice, buffering you against the life-payment cost demanded by Bolas's Citadel. That very same Citadel is the engine that lets you recast Myr Scrapling straight off the top of your library for life instead of mana, looping the entire process endlessly to fuel your storm count and pump Carmen to astronomical proportions.