Mortuary + Skirk Prospector + Bolas's Citadel + Overgrowth Elemental

Mortuary

Skirk Prospector

Bolas's Citadel

Overgrowth Elemental

How it works

1. Activate Skirk Prospector by sacrificing it.
2. When Skirk Prospector dies, Mortuary and Overgrowth Elemental trigger.
3. Resolve the Mortuary trigger, putting Skirk Prospector from your graveyard onto the top of your library.
4. Resolve the Overgrowth Elemental trigger, causing you to gain 1 life
5. Cast Skirk Prospector from the top of your library by paying 1 life.
6. Repeat.

This elegant loop lets you turn a single Goblin into an endless engine of sacrifice and rebirth, fueled entirely by life rather than mana. With Bolas's Citadel in play, you gain the ability to cast Skirk Prospector directly from the top of your library for a mere 1 life instead of its usual cost. As the Prospector is sacrificed to its own ability for red mana, Mortuary gently intercepts the creature on its way to the graveyard, placing it right back on top of your library to repeat the process. Meanwhile, Overgrowth Elemental watches the carnage unfold, turning every single iteration of this cycle into a steady stream of lifegain that comfortably offsets the life you pay to Bolas's Citadel.