Mortuary + Thermopod + Bolas's Citadel + Haywire Mite

Mortuary

Thermopod

Bolas's Citadel

Haywire Mite

How it works

1. Activate Thermopod by sacrificing Haywire Mite.
2. When Haywire Mite dies, it and Mortuary triggers.
3. Resolve the Mortuary trigger, putting Haywire Mite from your graveyard onto the top of your library.
4. Resolve the Haywire Mite trigger, causing you to gain 2 life
5. Cast Haywire Mite from the top of your library by paying 1 life due to Bolas's Citadel.
6. Repeat.

This loop creates an engine by leveraging Bolas's Citadel to cast spells straight from the top of your library using life instead of mana. When you sacrifice Haywire Mite to Thermopod for red mana, Mortuary catches the creature as it hits the graveyard and immediately places it right back onto the top of your library. Because Haywire Mite's death also triggers its own ability to gain you 2 life, the net result is a positive life swing that easily pays for Bolas's Citadel's life-payment cost to recast the Mite over and over again.