Ben-Ben, Akki Hermit

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

Iron Myr

Red Elemental Blast

Choose one —
• Counter target blue spell.
• Destroy target blue permanent.

Scythe of the Wretched

Equipped creature gets +2/+2.
Whenever a creature dealt damage by equipped creature this turn dies, return that card to the battlefield under your control. Attach Scythe of the Wretched to that creature.
Equip {4}

Earth Servant

Earth Servant gets +0/+1 for each Mountain you control.

Journeyer's Kite

{3}, {T}: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Goblin Diplomats

{T}: Each creature attacks this turn if able.

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.

Tectonic Reformation

Each land card in your hand has cycling {R}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Rage Nimbus

Defender, flying
{1}{R}: Target creature attacks this turn if able.

Goblin Charbelcher

{3}, {T}: Reveal cards from the top of your library until you reveal a land card. Goblin Charbelcher deals damage equal to the number of nonland cards revealed this way to any target. If the revealed land card was a Mountain, Goblin Charbelcher deals double that damage instead. Put the revealed cards on the bottom of your library in any order.

Akoum Hellkite

Flying
Landfall — Whenever a land enters the battlefield under your control, Akoum Hellkite deals 1 damage to any target. If that land is a Mountain, Akoum Hellkite deals 2 damage instead.

Spitting Earth

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

Spire Barrage

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

Blood Moon

Guttersnipe

Whenever you cast an instant or sorcery spell, Guttersnipe deals 2 damage to each opponent.

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.

Claws of Valakut

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

Chandra's Regulator

Whenever you activate a loyalty ability of a Chandra planeswalker, you may pay {1}. If you do, copy that ability. You may choose new targets for the copy.
{1}, {T}, Discard a Mountain card or a red card: Draw a card.

Coalhauler Swine

Whenever Coalhauler Swine is dealt damage, it deals that much damage to each player.

Fumiko the Lowblood

Fumiko the Lowblood has bushido X, where X is the number of attacking creatures. (Whenever this creature blocks or becomes blocked, it gets +X/+X until end of turn.)
Creatures your opponents control attack each combat if able.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Granite Grip

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

Seer's Sundial

Landfall — Whenever a land enters the battlefield under your control, you may pay {2}. If you do, draw a card.

Scaretiller

Whenever Scaretiller becomes tapped, choose one —
• You may put a land card from your hand onto the battlefield tapped.
• Return target land card from your graveyard to the battlefield tapped.

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.

Farfinder

Vigilance
When Farfinder enters the battlefield, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

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.'"

Magus of the Moon

Valakut, the Molten Pinnacle

Valakut, the Molten Pinnacle enters the battlefield tapped.
Whenever a Mountain enters the battlefield under your control, if you control at least five other Mountains, you may have Valakut, the Molten Pinnacle deal 3 damage to any target.
{T}: Add {R}.

Walking Atlas

{T}: You may put a land card from your hand onto the battlefield.

Tunneling Geopede

Landfall — Whenever a land enters the battlefield under your control, Tunneling Geopede deals 1 damage to each opponent.

Snow-Covered Mountain

Cosi's Ravager

Landfall — Whenever a land enters the battlefield under your control, you may have Cosi's Ravager deal 1 damage to target player or planeswalker.

Solemn Simulacrum

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

Mogg Maniac

Whenever Mogg Maniac is dealt damage, it deals that much damage to target opponent or planeswalker.

Anger

Haste
As long as Anger is in your graveyard and you control a Mountain, creatures you control have haste.

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.

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.

Electrostatic Field

Defender
Whenever you cast an instant or sorcery spell, Electrostatic Field deals 1 damage to each opponent.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Spawn of Thraxes

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

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.

Arcbond

Choose target creature. Whenever that creature is dealt damage this turn, it deals that much damage to each other creature and each player.

Curse of Opulence

Enchant player
Whenever enchanted player is attacked, create a Gold token. Each opponent attacking that player does the same. (A Gold token is an artifact with "Sacrifice this artifact: Add one mana of any color.")

Obsidian Fireheart

{1}{R}{R}: Put a blaze counter on target land without a blaze counter on it. For as long as that land has a blaze counter on it, it has "At the beginning of your upkeep, this land deals 1 damage to you." (The land continues to burn after Obsidian Fireheart has left the battlefield.)

Endless Atlas

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

Goblin Spymaster

First strike
At the beginning of each opponent's end step, that player creates a 1/1 red Goblin creature token with "Creatures you control attack each combat if able."

Skred

Skred deals damage to target creature equal to the number of snow permanents you control.

Chain Reaction

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

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Lithoform Engine

{2}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}, {T}: Copy target permanent spell you control. (The copy becomes a token.)

Myriad Landscape

Myriad Landscape enters the battlefield tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Seismic Strike

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

Dragonmaster Outcast

At the beginning of your upkeep, if you control six or more lands, create a 5/5 red Dragon creature token with flying.

Sol Ring

Ghirapur Orrery

Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.

Thrill of Possibility

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

Burnished Hart

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

Nyx Lotus

Nyx Lotus enters the battlefield tapped.
{T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Pilgrim's Eye

Flying
When Pilgrim's Eye enters the battlefield, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Deflecting Swat

If you control a commander, you may cast this spell without paying its mana cost.
You may choose new targets for target spell or ability.

Charmbreaker Devils

At the beginning of your upkeep, return an instant or sorcery card at random from your graveyard to your hand.
Whenever you cast an instant or sorcery spell, Charmbreaker Devils gets +4/+0 until end of turn.

Stuffy Doll

Indestructible
As Stuffy Doll enters the battlefield, choose a player.
Whenever Stuffy Doll is dealt damage, it deals that much damage to the chosen player.
{T}: Stuffy Doll deals 1 damage to itself.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Rockslide Ambush

Rockslide Ambush deals damage to target creature equal to the number of Mountains you control.