Flame Burst

Flame Burst deals X damage to any target, where X is 2 plus the number of cards named Flame Burst in all graveyards.

Searing Spear

Searing Spear deals 3 damage to any target.

Fight with Fire

Kicker {5}{R} (You may pay an additional {5}{R} as you cast this spell.)
Fight with Fire deals 5 damage to target creature. If this spell was kicked, it deals 10 damage divided as you choose among any number of targets instead. (Those targets can include players and planeswalkers.)

Chandra's Spitfire

Flying
Whenever an opponent is dealt noncombat damage, Chandra's Spitfire gets +3/+0 until end of turn.

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Pyroclasm

Pyroclasm deals 2 damage to each creature.

Firebolt

Firebolt deals 2 damage to any target.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mountain

The Flame of Keld

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Discard your hand.
II — Draw two cards.
III — If a red source you control would deal damage to a permanent or player this turn, it deals that much damage plus 2 to that permanent or player instead.