Mortuary + Bolas's Citadel + Goblin Firestarter + Blood Artist

Mortuary

Bolas's Citadel

Goblin Firestarter

Blood Artist

How it works

1. Activate Goblin Firestarter by sacrificing it.
2. When Goblin Firestarter dies, Mortuary and Blood Artist trigger.
3. Resolve the Mortuary trigger, putting Goblin Firestarter from your graveyard onto the top of your library.
4. Resolve the Blood Artist trigger, causing you to gain 1 life and target opponent to lose 1 life.
5. Resolve the Goblin Firestarter ability.
6. Cast Goblin Firestarter from the top of your library by paying 1 life.
7. Repeat.

This clever loop bypasses conventional mana entirely by letting Bolas's Citadel cast spells straight off the top of your library for a mere sliver of life instead of their mana costs. You simply sacrifice Goblin Firestarter to ping any target, triggering Blood Artist to pad your life total while draining an opponent. Meanwhile, Mortuary ensures that the fallen Goblin Firestarter never actually stays in the graveyard, instantly sliding it back to the top of your library so Bolas's Citadel can cast it all over again.