Mortuary + Thermopod + Bolas's Citadel + Serrated Scorpion

Mortuary

Thermopod

Bolas's Citadel

Serrated Scorpion

How it works

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

This clever loop lets you turn a humble insect into an entire win condition by leveraging Bolas's Citadel to cast spells straight from the top of your library using life instead of mana. When you sacrifice Serrated Scorpion to Thermopod for red mana, Mortuary catches the creature as it hits the graveyard and immediately places it right back onto your library. Meanwhile, the Scorpion's own death trigger drains your opponents and pads your life total just enough to continually pay the Citadel's life-based casting cost, keeping the engine churning endlessly.