Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

Wall of Stone

Volcanic Hammer

Volcanic Hammer deals 3 damage to any target.

Jaws of Stone

Jaws of Stone deals X damage divided as you choose among any number of targets, where X is the number of Mountains you control as you cast this spell.

Volcanic Wind

Volcanic Wind deals X damage divided as you choose among any number of target creatures, where X is the number of creatures on the battlefield as you cast this spell.

Lavabrink Floodgates

{T}: Add {R}{R}.
At the beginning of each player's upkeep, that player may put a doom counter on Lavabrink Floodgates or remove a doom counter from it. Then if it has three or more doom counters on it, sacrifice Lavabrink Floodgates. When you do, it deals 6 damage to each creature.

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Claws of Valakut

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

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Koth of the Hammer

+1: Untap target Mountain. It becomes a 4/4 red Elemental creature until end of turn. It's still a land.
−2: Add {R} for each Mountain you control.
−5: You get an emblem with "Mountains you control have '{T}: This land deals 1 damage to any target.'"

Chartooth Cougar

{R}: Chartooth Cougar 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.)

Jiwari, the Earth Aflame

{X}{R}, {T}: Jiwari, the Earth Aflame deals X damage to target creature without flying.
Channel — {X}{R}{R}{R}, Discard Jiwari: Jiwari deals X damage to each creature without flying.

Granite Grip

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

Molten Disaster

Kicker {R} (You may pay an additional {R} as you cast this spell.)
If this spell was kicked, it has split second. (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Molten Disaster deals X damage to each creature without flying and each player.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Aftershock

Destroy target artifact, creature, or land. Aftershock deals 3 damage to you.

Wall of Lava

Defender (This creature can't attack.)
{R}: Wall of Lava gets +1/+1 until end of turn.

Toggo, Goblin Weaponsmith

Landfall — Whenever a land you control enters, create a colorless Equipment artifact token named Rock with "Equipped creature has '{1}, {T}, Sacrifice Rock: This creature deals 2 damage to any target'" and equip {1}.
Partner (You can have two commanders if both have partner.)

Volcanic Offering

Destroy target nonbasic land you don't control and target nonbasic land of an opponent's choice you don't control.
Volcanic Offering deals 7 damage to target creature you don't control and 7 damage to target creature of an opponent's choice you don't control.

Spawn of Thraxes

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

Seismic Strike

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

Endless Atlas

{2}, {T}: Draw a card. Activate only if you control three or more lands with the same name.

Shatterskull, the Hammer Pass

As Shatterskull, the Hammer Pass enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {R}.

Shatterskull Smashing

Shatterskull Smashing deals X damage divided as you choose among up to two target creatures and/or planeswalkers. If X is 6 or more, Shatterskull Smashing deals twice X damage divided as you choose among them instead.

Shatterskull Smashing // Shatterskull, the Hammer Pass

Stonefury

Stonefury deals damage to target creature equal to the number of lands you control.

Earthquake

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

Rock Slide

Rock Slide deals X damage divided as you choose among any number of target attacking or blocking creatures without flying.

Spitting Earth

Spitting Earth deals damage to target creature equal to the number of Mountains you control.

Volcanic Dragon

Magmaquake

Magmaquake deals X damage to each creature without flying and each planeswalker.

Armillary Sphere

{2}, {T}, Sacrifice Armillary Sphere: Search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.

Fire Diamond

Fire Diamond enters tapped.
{T}: Add {R}.

Lava Storm

Lava Storm deals 2 damage to each attacking creature or Lava Storm deals 2 damage to each blocking creature.

Volcanic Fallout

This spell can't be countered.
Volcanic Fallout deals 2 damage to each creature and each player.

Sudden Demise

Choose a color. Sudden Demise deals X damage to each creature of the chosen color.

Spire Barrage

Spire Barrage deals damage to any target equal to the number of Mountains you control.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
Everflowing Chalice enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on Everflowing Chalice.

Mana Geyser

Add {R} for each tapped land your opponents control.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Ben-Ben, Akki Hermit

{T}: Ben-Ben, Akki Hermit deals damage to target attacking creature equal to the number of untapped Mountains you control.

Volcanic Submersion

Destroy target artifact or land.
Cycling {2} ({2}, Discard this card: Draw a card.)

Contagion Clasp

When Contagion Clasp enters, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Commune with Lava

Exile the top X cards of your library. Until the end of your next turn, you may play those cards.

Slagstorm

Choose one —
• Slagstorm deals 3 damage to each creature.
• Slagstorm deals 3 damage to each player.

Stone Idol Trap

This spell costs {1} less to cast for each attacking creature.
Create a 6/12 colorless Construct artifact creature token with trample. Exile it at the beginning of your next end step.

Downhill Charge

You may sacrifice a Mountain rather than pay this spell's mana cost.
Target creature gets +X/+0 until end of turn, where X is the number of Mountains you control.

Flametongue Kavu

When Flametongue Kavu enters, it deals 4 damage to target creature.

Outpost Siege

As Outpost Siege enters, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card.
• Dragons — Whenever a creature you control leaves the battlefield, Outpost Siege deals 1 damage to any target.

Fault Line

Fault Line deals X damage to each creature without flying and each player.

Magmatic Insight

As an additional cost to cast this spell, discard a land card.
Draw two cards.

Repeated Reverberation

When you next cast an instant spell, cast a sorcery spell, or activate a loyalty ability this turn, copy that spell or ability twice. You may choose new targets for the copies.

Landslide

Sacrifice any number of Mountains. Landslide deals that much damage to target player or planeswalker.

Burnished Hart

{3}, Sacrifice this creature: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Volt Charge

Volt Charge deals 3 damage to any target. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Siege of Towers

Replicate {1}{R} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Target Mountain becomes a 3/1 creature. It's still a land.

Oxidda Golem

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

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Wall of Earth

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Volcanic Vision

Return target instant or sorcery card from your graveyard to your hand. Volcanic Vision deals damage equal to that card's mana value to each creature your opponents control. Exile Volcanic Vision.