Mortuary + Bolas's Citadel + Goblin Firestarter + Overgrowth Elemental

Mortuary

Bolas's Citadel

Goblin Firestarter

Overgrowth Elemental

How it works

1. Activate Goblin Firestarter by tapping and sacrificing it.
2. When Goblin Firestarter dies, Mortuary and Overgrowth Elemental trigger.
3. Resolve the Mortuary trigger, putting Goblin Firestarter from your graveyard onto the top of your library.
4. Resolve the Overgrowth Elemental trigger, causing you to gain 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 self-sustaining loop turns a humble goblin into an engine of infinite devastation, all fueled by paying life instead of mana through Bolas's Citadel. Whenever you sacrifice Goblin Firestarter to ping any target, Mortuary immediately intercepts it on the way to the graveyard to stack it right back onto the top of your library. Meanwhile, Overgrowth Elemental watches the creature die to restore your life total and completely negate the life cost of recasting the goblin.