Mortuary + Bolas's Citadel + Bloodflow Connoisseur + Serrated Scorpion

Mortuary

Bolas's Citadel

Bloodflow Connoisseur

Serrated Scorpion

How it works

1. Activate Bloodflow Connoisseur 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. Resolve the Bloodflow Connoisseur ability.
6. Cast Serrated Scorpion from the top of your library by paying 1 life due to Bolas's Citadel.
7. Repeat.

This elegant little engine turns your library into a self-sustaining loop by leveraging Bolas's Citadel to cast spells right off the top using life instead of mana. Bloodflow Connoisseur acts as the active sacrifice outlet, letting you feed Serrated Scorpion into the graveyard over and over while growing larger with every iteration. Every time that Scorpion dies, Mortuary neatly recycles it back to the very top of your library so Bolas's Citadel can immediately play it again for a mere 1 life. Meanwhile, Serrated Scorpion's own death trigger easily outpaces the life you pay, draining your opponents out of the game while simultaneously padding your own life total.