Activate Fanatical Firebrand by tapping and sacrificing it.
When Fanatical Firebrand dies, Luminous Broodmoth triggers, returning Fanatical Firebrand from your graveyard to the battlefield without a flying counter on it due to Solemnity.
Resolve the Fanatical Firebrand ability.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Infinite damage

Solemnity

Luminous Broodmoth

Fanatical Firebrand

Activate Fanatical Firebrand by tapping and sacrificing it.
When Fanatical Firebrand dies, Mortuary and Vindictive Vampire trigger.
Resolve the Mortuary trigger, putting Fanatical Firebrand from your graveyard onto the top of your library.
Resolve the Vindictive Vampire trigger, dealing 1 damage to each opponent and causing you to gain 1 life.
Resolve the Fanatical Firebrand ability.
Cast Fanatical Firebrand from the top of your library by paying 1 life.
Repeat.

Infinite lifegain triggers

Infinite storm count

Mortuary

Vindictive Vampire

Gwenom, Remorseless

Activate Fanatical Firebrand by tapping and sacrificing it.
When Fanatical Firebrand dies, Yedora triggers, returning Fanatical Firebrand from your graveyard to the battlefield face-down as a Forest land.
When Fanatical Firebrand enters the battlefield, Zimone triggers.
Holding priority, activate Fanatical Firebrand by tapping it, adding {G}.
Resolve the Zimone trigger, turning Fanatical Firebrand face-up.
Resolve the Fanatical Firebrand ability from step 1.
Repeat.

Infinite green mana

Infinite landfall triggers

Zimone, Mystery Unraveler

Yedora, Grave Gardener

Combos with "Fanatical Firebrand"