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.

Highland Forest

({T}: Add {R} or {G}.)
This land enters tapped.

Wooded Foothills

{T}, Pay 1 life, Sacrifice this land: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Igneous Pouncer

Haste
Swampcycling {2}, mountaincycling {2} ({2}, Discard this card: Search your library for a Swamp or Mountain card, reveal it, put it into your hand, then shuffle.)

Zodiac Dog

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Garth One-Eye

{T}: Choose a card name that hasn't been chosen from among Disenchant, Braingeyser, Terror, Shivan Dragon, Regrowth, and Black Lotus. Create a copy of the card with the chosen name. You may cast the copy. (You still pay its costs.)

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.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Awaken the Ancient

Enchant Mountain
Enchanted Mountain is a 7/7 red Giant creature with haste. It's still a land.

Zodiac Goat

Savai Triome

({T}: Add {R}, {W}, or {B}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Blood Crypt

({T}: Add {B} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Ben-Ben, Akki Hermit

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

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}.

Wild Nacatl

This creature gets +1/+1 as long as you control a Mountain.
This creature gets +1/+1 as long as you control a Plains.

Rockslide Ambush

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

Gauntlet of Might

Red creatures get +1/+1.
Whenever a Mountain is tapped for mana, its controller adds an additional {R}.

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.'"

Canyon Wildcat

Flameshot

You may discard a Mountain card rather than pay this spell's mana cost.
Flameshot deals 3 damage divided as you choose among one, two, or three target creatures.

Plateau

Last Stand

Target opponent loses 2 life for each Swamp you control. Last Stand deals damage to target creature equal to the number of Mountains you control. Create a 1/1 green Saproling creature token for each Forest you control. You gain 2 life for each Plains you control. Draw a card for each Island you control, then discard that many cards.

Stomping Ground

({T}: Add {R} or {G}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Keeper of Progenitus

Whenever a player taps a Mountain, Forest, or Plains for mana, that player adds one mana of any type that land produced.

Maestros Theater

When this land enters, sacrifice it. When you do, search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Volatile Fjord

({T}: Add {U} or {R}.)
This land enters tapped.

Firecat Blitz

Create X 1/1 red Elemental Cat creature tokens with haste. Exile them at the beginning of the next end step.
Flashback—{R}{R}, Sacrifice X Mountains. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Blood Moon

Lava Dart

Lava Dart deals 1 damage to any target.
Flashback—Sacrifice a Mountain. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Chained to the Rocks

Enchant Mountain you control
When this Aura enters, exile target creature an opponent controls until this Aura leaves the battlefield. (That creature returns under its owner's control.)

Dwarven Mine

({T}: Add {R}.)
This land enters tapped unless you control three or more other Mountains.
When this land enters untapped, create a 1/1 red Dwarf creature token.

Geothermal Bog

({T}: Add {B} or {R}.)
This land enters tapped.

Sulfurous Mire

Eternal Flame

Eternal Flame deals X damage to target opponent or planeswalker and half X damage, rounded up, to you, where X is the number of Mountains you control.

Landslide

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

Noggle Hedge-Mage

When this creature enters, if you control two or more Islands, you may tap two target permanents.
When this creature enters, if you control two or more Mountains, you may have this creature deal 2 damage to target player or planeswalker.

Bloodstained Mire

{T}, Pay 1 life, Sacrifice this land: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

Dominaria's Judgment

Until end of turn, creatures you control gain protection from white if you control a Plains, from blue if you control an Island, from black if you control a Swamp, from red if you control a Mountain, and from green if you control a Forest.

Akoum Hellkite

Flying
Landfall — Whenever a land you control enters, this creature deals 1 damage to any target. If that land is a Mountain, this creature deals 2 damage instead.

Alpine Guide

When this creature enters, you may search your library for a Mountain card, put that card onto the battlefield tapped, then shuffle.
This creature attacks each combat if able.
When this creature leaves the battlefield, sacrifice a Mountain.

Molten Tributary

Seismic Strike

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

Riveteers Overlook

When this land enters, sacrifice it. When you do, search your library for a basic Swamp, Mountain, or Forest card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

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.)

Xander's Lounge

({T}: Add {U}, {B}, or {R}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Cliff Threader

Chaos Moon

At the beginning of each upkeep, count the number of permanents. If the number is odd, until end of turn, red creatures get +1/+1 and whenever a player taps a Mountain for mana, that player adds an additional {R}. If the number is even, until end of turn, red creatures get -1/-1 and if a player taps a Mountain for mana, that Mountain produces colorless mana instead of any other type.

Ketria Triome

({T}: Add {G}, {U}, or {R}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Cinder Glade

({T}: Add {R} or {G}.)
This land enters tapped unless you control two or more basic lands.

Canyon Slough

({T}: Add {B} or {R}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Scalding Tarn

{T}, Pay 1 life, Sacrifice this land: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Spawn of Thraxes

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

Koth, Fire of Resistance

+2: Search your library for a basic Mountain card, reveal it, put it into your hand, then shuffle.
−3: Koth deals damage to target creature equal to the number of Mountains you control.
−7: You get an emblem with "Whenever a Mountain you control enters, this emblem deals 4 damage to any target."

Earth Servant

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

Wooded Ridgeline

Shard Convergence

Search your library for a Plains card, an Island card, a Swamp card, and a Mountain card. Reveal those cards, put them into your hand, then shuffle.

Ruin Grinder

Menace
When this creature dies, each player may discard their hand and draw seven cards.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

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.

Spitting Earth

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

Taiga

Goblin Mountaineer

Spire Barrage

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

Raugrin Triome

({T}: Add {U}, {R}, or {W}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Badlands

Cabaretti Courtyard

When this land enters, sacrifice it. When you do, search your library for a basic Mountain, Forest, or Plains card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Magus of the Moon

Valley Rannet

Mountaincycling {2}, forestcycling {2} ({2}, Discard this card: Search your library for a Mountain or Forest card, reveal it, put it into your hand, then shuffle.)

Claws of Valakut

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

Smoldering Marsh

({T}: Add {B} or {R}.)
This land enters tapped unless you control two or more basic lands.

Goblin Spelunkers

Flinthoof Boar

This creature gets +1/+1 as long as you control a Mountain.
{R}: This creature gains haste until end of turn. (It can attack and {T} this turn.)

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.

Kyren Legate

If an opponent controls a Plains and you control a Mountain, you may cast this spell without paying its mana cost.
Haste

Crash

You may sacrifice a Mountain rather than pay this spell's mana cost.
Destroy target artifact.

Goblin Charbelcher

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

Sheltered Thicket

({T}: Add {R} or {G}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Mountain

Duergar Hedge-Mage

When this creature enters, if you control two or more Mountains, you may destroy target artifact.
When this creature enters, if you control two or more Plains, you may destroy target enchantment.

Oxidda Golem

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

Spoils of Victory

Search your library for a Plains, Island, Swamp, Mountain, or Forest card and put that card onto the battlefield. Then shuffle.

Steam Vents

({T}: Add {U} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Arid Mesa

{T}, Pay 1 life, Sacrifice this land: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Gem of Becoming

{3}, {T}, Sacrifice this artifact: Search your library for an Island card, a Swamp card, and a Mountain card. Reveal those cards, put them into your hand, then shuffle.

Dwarven Grunt

Sardian Cliffstomper

As long as it's your turn and you control four or more Mountains, this creature gets +X/+0, where X is the number of Mountains you control.

Barrel Down Sokenzan

Sweep — Return any number of Mountains you control to their owner's hand. Barrel Down Sokenzan deals damage to target creature equal to twice the number of Mountains returned this way.

Mountain Goat

Granite Grip

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

Sacred Peaks

({T}: Add {R} or {W}.)
This land enters tapped.

Anger

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

The First Eruption

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga deals 1 damage to each creature without flying.
II — Add {R}{R}.
III — Sacrifice a Mountain. If you do, this Saga deals 3 damage to each creature.

Pulverize

You may sacrifice two Mountains rather than pay this spell's mana cost.
Destroy all artifacts.

Sacred Foundry

({T}: Add {R} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Alpine Meadow

Fire Dragon

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

Volcanic Island

Goblins of the Flarg

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)
When you control a Dwarf, sacrifice this creature.

Ziatora's Proving Ground

({T}: Add {B}, {R}, or {G}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Jetmir's Garden

({T}: Add {R}, {G}, or {W}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)