Prodigal Pyromancer

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

Claws of Valakut

Enchant creature
Enchanted creature gets +1/+0 for each Mountain you control and has first strike.

Seismic Strike

Seismic Strike deals damage to target creature equal to the number of Mountains you control.

Spawn of Thraxes

Flying
When this creature enters, it deals damage to any target equal to the number of Mountains you control.

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Mountain

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.

Punishing Fire

Punishing Fire deals 2 damage to any target.
Whenever an opponent gains life, you may pay {R}. If you do, return this card from your graveyard to your hand.

Raging Goblin

Haste (This creature can attack and {T} as soon as it comes under your control.)

Fire Servant

If a red instant or sorcery spell you control would deal damage, it deals double that damage instead.

Sparkmage Apprentice

When this creature enters, it deals 1 damage to any target.

Glass Golem

Demolish

Earth Servant

This creature gets +0/+1 for each Mountain you control.

Incinerate

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

Chandra's Outrage

Chandra's Outrage deals 4 damage to target creature and 2 damage to that creature's controller.

Lightning Elemental

Valakut, the Molten Pinnacle

This land enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have this land deal 3 damage to any target.
{T}: Add {R}.

Arc Runner

Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice this creature.

Ogre's Cleaver

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Teetering Peaks

This land enters tapped.
When this land enters, target creature gets +2/+0 until end of turn.
{T}: Add {R}.

Chandra's Spitfire

Flying
Whenever an opponent is dealt noncombat damage, this creature gets +3/+0 until end of turn.