Mortuary + Moldervine Reclamation + Bolas's Citadel + Fanatical Firebrand

Mortuary

Moldervine Reclamation

Bolas's Citadel

Fanatical Firebrand

How it works

1. Activate Fanatical Firebrand by sacrificing it.
2. When Fanatical Firebrand dies, Mortuary and Moldervine Reclamation trigger.
3. Resolve the Moldervine Reclamation trigger, causing you to gain 1 life and draw a card.
4. Resolve the Mortuary trigger, putting Fanatical Firebrand from your graveyard onto the top of your library.
5. Resolve the Fanatical Firebrand ability.
6. Cast Fanatical Firebrand from the top of your library by paying 1 life.
7. Repeat.

This looping engine turns a single goblin into a self-sustaining machine by leveraging Bolas's Citadel to cast spells straight from the top of your library for life instead of mana. When you activate Fanatical Firebrand to ping a target and send it to the graveyard, Mortuary quietly intercepts it to place the card right back on top of your library. Meanwhile, Moldervine Reclamation takes advantage of the creature's demise to replenish your hand and offset the life paid to the Citadel. Because the mana cost is bypassed entirely, you can replay the Fanatical Firebrand over and over again, easily converting a single life point per iteration into an unstoppable torrent of damage and card draw.