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."

Tectonic Instability

Whenever a land enters, tap all lands its controller controls.

Roiling Terrain

Destroy target land, then Roiling Terrain deals damage to that land's controller equal to the number of land cards in that player's graveyard.

Mountain

Keldon Firebombers

When Keldon Firebombers enters, each player sacrifices all lands they control except for three.

Tunnel Ignus

Whenever a land enters under an opponent's control, if that player had another land enter the battlefield under their control this turn, Tunnel Ignus deals 3 damage to that 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.

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of each of your postcombat main phases, add {R} for each 1 life your opponents have lost this turn.

Tectonic Break

Each player sacrifices X lands of their choice.

Crucible of Worlds

Detritivore

Detritivore's power and toughness are each equal to the number of nonbasic land cards in your opponents' graveyards.
Suspend X—{X}{3}{R}. X can't be 0. (Rather than cast this card from your hand, you may pay {X}{3}{R} and exile it with X time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)
Whenever a time counter is removed from Detritivore while it's exiled, destroy target nonbasic land.

Big Score

As an additional cost to cast this spell, discard a card.
Draw two cards and create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Solphim, Mayhem Dominus

If a source you control would deal noncombat damage to an opponent or a permanent an opponent controls, it deals double that damage to that player or permanent instead.
{1}{R/P}{R/P}, Discard two cards: Put an indestructible counter on Solphim, Mayhem Dominus. ({R/P} can be paid with either {R} or 2 life.)

Dwarven Driller

{T}: Destroy target land unless its controller has Dwarven Driller deal 2 damage to them.

Iron Myr

Bust

Boom

Destroy target land you control and target land you don't control.

Boom // Bust

The Great Work

(As this Saga enters and after your draw step, add a lore counter.)
I — The Great Work deals 3 damage to target opponent and each creature they control.
II — Create three Treasure tokens.
III — Until end of turn, you may cast instant and sorcery spells from any graveyard. If a spell cast this way would be put into a graveyard, exile it instead. Exile The Great Work, then return it to the battlefield (front face up).

Urabrask

First strike
Whenever you cast an instant or sorcery spell, Urabrask deals 1 damage to target opponent. Add {R}.
{R}: Exile Urabrask, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery and only if you've cast three or more instant and/or sorcery spells this turn.

Urabrask // The Great Work

From the Ashes

Destroy all nonbasic lands. For each land destroyed this way, its controller may search their library for a basic land card and put it onto the battlefield. Then each player who searched their library this way shuffles.

Star of Extinction

Destroy target land. Star of Extinction deals 20 damage to each creature and each planeswalker.

Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Commander's Sphere

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

Invader Parasite

Imprint — When Invader Parasite enters, exile target land.
Whenever a land an opponent controls with the same name as the exiled card enters, Invader Parasite deals 2 damage to that player.

Obliterate

This spell can't be countered.
Destroy all artifacts, creatures, and lands. They can't be regenerated.

Eidolon of the Great Revel

Whenever a player casts a spell with mana value 3 or less, Eidolon of the Great Revel deals 2 damage to that player.

Geomancer's Gambit

Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.
Draw a card.

Furnace Punisher

Menace
At the beginning of each player's upkeep, Furnace Punisher deals 2 damage to that player unless they control two or more basic lands.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.

Stoneshaker Shaman

At the beginning of each player's end step, that player sacrifices an untapped land of their choice.

Zo-Zu the Punisher

Whenever a land enters, Zo-Zu the Punisher deals 2 damage to that land's controller.

Harsh Mentor

Whenever an opponent activates an ability of an artifact, creature, or land on the battlefield, if it isn't a mana ability, Harsh Mentor deals 2 damage to that player.

Seismic Spike

Cemetery Gatekeeper

First strike
When Cemetery Gatekeeper enters, exile a card from a graveyard.
Whenever a player plays a land or casts a spell, if it shares a card type with the exiled card, Cemetery Gatekeeper deals 2 damage to that player.

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.

Wake of Destruction

Destroy target land and all other lands with the same name as that land.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.

Cleansing Wildfire

Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.
Draw a card.

Jokulhaups

Destroy all artifacts, creatures, and lands. They can't be regenerated.

Epicenter

Target player sacrifices a land of their choice.
Threshold — Each player sacrifices all lands they control instead if seven or more cards are in your graveyard.

Mine Layer

{1}{R}, {T}: Put a mine counter on target land.
Whenever a land with a mine counter on it becomes tapped, destroy it.
When Mine Layer leaves the battlefield, remove all mine counters from all lands.

Wildfire

Each player sacrifices four lands of their choice. Wildfire deals 4 damage to each creature.

Decree of Annihilation

Exile all artifacts, creatures, and lands from the battlefield, all cards from all graveyards, and all cards from all hands.
Cycling {5}{R}{R} ({5}{R}{R}, Discard this card: Draw a card.)
When you cycle Decree of Annihilation, destroy all lands.

Fire Diamond

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

Immolation Shaman

Whenever an opponent activates an ability of an artifact, creature, or land that isn't a mana ability, Immolation Shaman deals 1 damage to that player.
{3}{R}{R}: Immolation Shaman gets +3/+3 and gains menace until end of turn.

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.

Dingus Egg

Whenever a land is put into a graveyard from the battlefield, Dingus Egg deals 2 damage to that land's controller.

Destructive Force

Each player sacrifices five lands of their choice. Destructive Force deals 5 damage to each creature.

Arcane Signet

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

Demolition Field

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Destroy target nonbasic land an opponent controls. That land's controller may search their library for a basic land card, put it onto the battlefield, then shuffle. You may search your library for a basic land card, put it onto the battlefield, then shuffle.

Darksteel Ingot

Indestructible (Effects that say "destroy" don't destroy this artifact.)
{T}: Add one mana of any color.

Mechanized Warfare

If a red or artifact source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 1 instead.

Zealous Conscripts

Haste
When Zealous Conscripts enters, gain control of target permanent until end of turn. Untap that permanent. It gains haste until end of turn.

Dwarven Blastminer

{2}{R}, {T}: Destroy target nonbasic land.
Morph {R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Mycosynth Lattice

All permanents are artifacts in addition to their other types.
All cards that aren't on the battlefield, spells, and permanents are colorless.
Players may spend mana as though it were mana of any color.

Impending Disaster

At the beginning of your upkeep, if there are seven or more lands on the battlefield, sacrifice Impending Disaster and destroy all lands.

Akki Blizzard-Herder

When Akki Blizzard-Herder dies, each player sacrifices a land of their choice.

Kiki-Jiki, Mirror Breaker

Haste
{T}: Create a token that's a copy of target nonlegendary creature you control, except it has haste. Sacrifice it at the beginning of the next end step.

Disrupt Decorum

Goad all creatures you don't control. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Myriad Landscape

Myriad Landscape enters 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.

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Ankh of Mishra

Whenever a land enters, Ankh of Mishra deals 2 damage to that land's controller.

Dwarven Miner

{2}{R}, {T}: Destroy target nonbasic land.

Orcish Settlers

{X}{X}{R}, {T}, Sacrifice Orcish Settlers: Destroy X target lands.

Elixir of Immortality

{2}, {T}: You gain 5 life. Shuffle Elixir of Immortality and your graveyard into their owner's library.