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.'"

Gamble

Search your library for a card, put that card into your hand, discard a card at random, then shuffle.

Jurassic Park

(Transforms from Welcome to ....)
Each Dinosaur card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.)
{T}: Add {G} for each Dinosaur you control.

Welcome to . . .

(As this Saga enters and after your draw step, add a lore counter.)
I — For each opponent, up to one target noncreature artifact they control becomes a 0/4 Wall artifact creature with defender for as long as you control this Saga.
II — Create a 3/3 green Dinosaur creature token with trample. It gains haste until end of turn.
III — Destroy all Walls. Exile this Saga, then return it to the battlefield transformed under your control.

Welcome to . . . // Jurassic Park

Fire Diamond

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

Seismic Strike

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

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.

Gauntlet of Might

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

Tempt with Discovery

Tempting offer — Search your library for a land card and put it onto the battlefield. Each opponent may search their library for a land card and put it onto the battlefield. For each opponent who searches a library this way, search your library for a land card and put it onto the battlefield. Then each player who searched a library this way shuffles.

Rockslide Ambush

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

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.

Highland Forest

({T}: Add {R} or {G}.)
Highland Forest enters tapped.

Exploration

You may play an additional land on each of your turns.

Furyborn Hellkite

Bloodthirst 6 (If an opponent was dealt damage this turn, this creature enters with six +1/+1 counters on it.)
Flying

Flinthoof Boar

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

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.

Splendid Reclamation

Return all land cards from your graveyard to the battlefield tapped.

Arid Archway

Arid Archway enters tapped.
When Arid Archway enters, return a land you control to its owner's hand. If another Desert was returned this way, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}{C}.

Staff of the Flame Magus

Whenever you cast a red spell or a Mountain you control enters, you gain 1 life.

Koth, Fire of Resistance

+2: Search your library for a basic Mountain card, reveal it, put it into your hand, then shuffle.
−3: Koth, Fire of Resistance 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."

Call for Aid

Gain control of all creatures target opponent controls until end of turn. Untap those creatures. They gain haste until end of turn. You can't attack that player this turn. You can't sacrifice those creatures this turn.

Bearer of the Heavens

When Bearer of the Heavens dies, destroy all permanents at the beginning of the next end step.

Wasteland

{T}: Add {C}.
{T}, Sacrifice Wasteland: Destroy target nonbasic land.

Granite Grip

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

Oxidda Golem

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

Ben-Ben, Akki Hermit

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

Genju of the Spires

Enchant Mountain
{2}: Enchanted Mountain becomes a 6/1 red Spirit creature until end of turn. It's still a land.
When enchanted Mountain is put into a graveyard, you may return Genju of the Spires from your graveyard to your hand.

Crash

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

Landslide

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

Sol Ring

Balduvian Trading Post

If Balduvian Trading Post would enter, sacrifice an untapped Mountain instead. If you do, put Balduvian Trading Post onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add {C}{R}.
{1}, {T}: Balduvian Trading Post deals 1 damage to target attacking creature.

Cinder Glade

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

Grand Warlord Radha

Haste
Whenever one or more creatures you control attack, add that much mana in any combination of {R} and/or {G}. Until end of turn, you don't lose this mana as steps and phases end.

Cave Sense

Enchant creature
Enchanted creature gets +1/+1 and has mountainwalk. (It can't be blocked as long as defending player controls a Mountain.)

Anger

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

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

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 Goblins of the Flarg.

The Lady of the Mountain

Dwarven Mine

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

Akoum Hellkite

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

Cactus Preserve

Cactus Preserve enters tapped.
{T}: Add one mana of any type that a land you control could produce.
{3}: Until end of turn, Cactus Preserve becomes an X/X green Plant creature with reach, where X is the greatest mana value among your commanders. It's still a land.

Magus of the Moon

Crucible of Worlds

Mirror of Galadriel

{5}, {T}: Scry 1, then draw a card. This ability costs {1} less to activate for each legendary creature you control.

Defense of the Heart

At the beginning of your upkeep, if an opponent controls three or more creatures, sacrifice Defense of the Heart, search your library for up to two creature cards, put those cards onto the battlefield, then shuffle.

Mountain Stronghold

Red legendary creatures you control have "bands with other legendary creatures." (Any legendary creatures can attack in a band as long as at least one has "bands with other legendary creatures." Bands are blocked as a group. If at least two legendary creatures you control, one of which has "bands with other legendary creatures," are blocking or being blocked by the same creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Strip Mine

{T}: Add {C}.
{T}, Sacrifice Strip Mine: Destroy target land.

Forest

Earth Servant

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

Commercial District

({T}: Add {R} or {G}.)
Commercial District enters tapped.
When Commercial District enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Fireblast

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

Magnetic Mountain

Blue creatures don't untap during their controllers' untap steps.
At the beginning of each player's upkeep, that player may choose any number of tapped blue creatures they control and pay {4} for each creature chosen this way. If the player does, untap those creatures.

Cunning Giant

If Cunning Giant is unblocked, you may have it assign its combat damage to a creature defending player controls.

Dining Room

Dining Room enters tapped.
{T}: Add {R} or {G}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Summit Apes

As long as you control a Mountain, Summit Apes has menace. (It can't be blocked except by two or more creatures.)

Undermountain Adventurer

Vigilance
When Undermountain Adventurer enters, you take the initiative.
{T}: Add {G}{G}. If you've completed a dungeon, add six {G} instead.

Bloodstained Mire

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

Sardian Cliffstomper

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

Torture Pit

If a source you control would deal noncombat damage to an opponent, it deals that much damage plus 2 instead.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Spiked Corridor

When you unlock this door, create three 1/1 red Devil creature tokens with "When this creature dies, it deals 1 damage to any target."
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Spiked Corridor // Torture Pit

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.

Valakut, the Molten Pinnacle

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

Stomping Ground

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

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.

There and Back Again

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Up to one target creature can't block for as long as you control There and Back Again. The Ring tempts you.
II — Search your library for a Mountain card, put it onto the battlefield, then shuffle.
III — Create Smaug, a legendary 6/6 red Dragon creature token with flying, haste, and "When this creature dies, create fourteen Treasure tokens."

Lithophage

At the beginning of your upkeep, sacrifice Lithophage unless you sacrifice a Mountain.

Boltbender

Disguise {1}{R} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When Boltbender is turned face up, you may choose new targets for any number of other spells and/or abilities.

Gaea's Cradle

{T}: Add {G} for each creature you control.

Shifting Woodland

Shifting Woodland enters tapped unless you control a Forest.
{T}: Add {G}.
Delirium — {2}{G}{G}: Shifting Woodland becomes a copy of target permanent card in your graveyard until end of turn. Activate only if there are four or more card types among cards in your graveyard.

Mountain

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.

Awaken the Ancient

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

Dormant Volcano

Dormant Volcano enters tapped.
When Dormant Volcano enters, sacrifice it unless you return an untapped Mountain you control to its owner's hand.
{T}: Add {C}{R}.

Ruby, Daring Tracker

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever Ruby attacks while you control a creature with power 4 or greater, Ruby gets +2/+2 until end of turn.
{T}: Add {R} or {G}.

Goblin Snowman

Whenever Goblin Snowman blocks, prevent all combat damage that would be dealt to and dealt by it this turn.
{T}: Goblin Snowman deals 1 damage to target creature it's blocking.

Sheltered Thicket

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

Taiga

Kyren Legate

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

Cave People

Whenever Cave People attacks, it gets +1/-2 until end of turn.
{1}{R}{R}, {T}: Target creature gains mountainwalk until end of turn. (It can't be blocked as long as defending player controls a Mountain.)

Fire Dragon

Flying
When Fire Dragon enters, it 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.

Burrowing

Enchant creature
Enchanted creature has mountainwalk. (It can't be blocked as long as defending player controls a Mountain.)

Rosheen, Roaring Prophet

When Rosheen, Roaring Prophet enters, mill six cards. You may put a card with {X} in its mana cost from among them into your hand.
{T}: Reveal any number of cards with {X} in their mana cost in your hand. Add {C}{C} for each card revealed this way. Spend this mana only on costs that contain {X}.

Gruul Signet

Wooded Ridgeline

({T}: Add {R} or {G}.)
Wooded Ridgeline enters tapped.

Themberchaud

Trample
When Themberchaud enters, he deals X damage to each other creature without flying and each player, where X is the number of Mountains you control.
You may exert Themberchaud as he attacks. When you do, he gains flying until end of turn. (An exerted creature won't untap during your next untap step.)

Temple of Cultivation

(Transforms from Ojer Kaslem, Deepest Growth.)
{T}: Add {G}.
{2}{G}, {T}: Transform Temple of Cultivation. Activate only if you control ten or more permanents and only as a sorcery.

Ojer Kaslem, Deepest Growth

Trample
Whenever Ojer Kaslem deals combat damage to a player, reveal that many cards from the top of your library. You may put a creature card and/or a land card from among them onto the battlefield. Put the rest on the bottom in a random order.
When Ojer Kaslem dies, return it to the battlefield tapped and transformed under its owner's control.

Ojer Kaslem, Deepest Growth // Temple of Cultivation

Spawn of Thraxes

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