Hostility

Haste
If a spell you control would deal damage to an opponent, prevent that damage. Create a 3/1 red Elemental Shaman creature token with haste for each 1 damage prevented this way.
When Hostility is put into a graveyard from anywhere, shuffle it into its owner's library.

Keldon Megaliths

This land enters tapped.
{T}: Add {R}.
Hellbent — {1}{R}, {T}: This land deals 1 damage to any target. Activate only if you have no cards in hand.

Demonfire

Demonfire deals X damage to any target. If a creature dealt damage this way would die this turn, exile it instead.
Hellbent — If you have no cards in hand, this spell can't be countered and the damage can't be prevented.

Fireblast

You may sacrifice two Mountains rather than pay this spell's mana cost.
Fireblast deals 4 damage to any target.

Fireslinger

{T}: This creature deals 1 damage to any target and 1 damage to you.

Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.

Chandra Nalaar

+1: Chandra Nalaar deals 1 damage to target player or planeswalker.
−X: Chandra Nalaar deals X damage to target creature.
−8: Chandra Nalaar deals 10 damage to target player or planeswalker and each creature that player or that planeswalker's controller controls.

Cone of Flame

Cone of Flame deals 1 damage to any target, 2 damage to another target, and 3 damage to a third target.

Soulbright Flamekin

{2}: Target creature gains trample until end of turn. If this is the third time this ability has resolved this turn, you may add {R}{R}{R}{R}{R}{R}{R}{R}.

Inner-Flame Acolyte

When this creature enters, target creature gets +2/+0 and gains haste until end of turn.
Evoke {R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Flamewave Invoker

{7}{R}: This creature deals 5 damage to target player or planeswalker.

Pyre Charger

Haste
{R}: This creature gets +1/+0 until end of turn.

Rakdos Pit Dragon

{R}{R}: This creature gains flying until end of turn.
{R}: This creature gets +1/+0 until end of turn.
Hellbent — This creature has double strike as long as you have no cards in hand.

Flametongue Kavu

When this creature enters, it deals 4 damage to target creature.

Flame Javelin

({2/R} can be paid with any two mana or with {R}. This card's mana value is 6.)
Flame Javelin deals 4 damage to any target.

Magma Jet

Magma Jet deals 2 damage to any target. Scry 2.

Mountain

Oxidda Golem

Affinity for Mountains (This spell costs {1} less to cast for each Mountain you control.)
Haste

Furnace Whelp

Flying
{R}: This creature gets +1/+0 until end of turn.

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.)

Ingot Chewer

When this creature enters, destroy target artifact.
Evoke {R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Seal of Fire

Sacrifice this enchantment: It deals 2 damage to any target.

Chartooth Cougar

{R}: This creature gets +1/+0 until end of turn.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Flamekin Brawler

{R}: This creature gets +1/+0 until end of turn.

Slith Firewalker

Haste
Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.

Incinerate

Incinerate deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.