Roadside Reliquary

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Draw a card if you control an artifact. Draw a card if you control an enchantment.

Crater Hellion

Echo {4}{R}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When this creature enters, it deals 4 damage to each other 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.

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Gilded Lotus

Oliphaunt

Trample
Whenever this creature attacks, another target creature you control gets +2/+0 and gains trample until end of turn.
Mountaincycling {1} ({1}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Purphoros, Bronze-Blooded

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Other creatures you control have haste.
{2}{R}: You may put a red creature card or an artifact creature card from your hand onto the battlefield. Sacrifice it at the beginning of the next end step.

Balefire Dragon

Flying
Whenever this creature deals combat damage to a player, it deals that much damage to each creature that player controls.

Spawn of Thraxes

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

Unexpected Windfall

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 token: Add one mana of any color.")

Terror of the Peaks

Flying
Spells your opponents cast that target this creature cost an additional 3 life to cast.
Whenever another creature you control enters, this creature deals damage equal to that creature's power to any target.

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."

Thrill of Possibility

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

Big Score

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.'"

Irencrag Feat

Add seven {R}. You can cast only one more spell this turn.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Mountain

Encroaching Wastes

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

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Drakuseth, Maw of Flames

Flying
Whenever Drakuseth attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Transmogrify

Exile target creature. That creature's controller reveals cards from the top of their library until they reveal a creature card. That player puts that card onto the battlefield, then shuffles the rest into their library.

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.

Meteor Golem

When this creature enters, destroy target nonland permanent an opponent controls.

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.)

God-Pharaoh's Gift

At the beginning of combat on your turn, you may exile a creature card from your graveyard. If you do, create a token that's a copy of that card, except it's a 4/4 black Zombie. It gains haste until end of turn.

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

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.)

The Autonomous Furnace

This land enters tapped.
{T}: Add {R}.
{1}{R}, {T}, Sacrifice this land: Draw a card.

Tyrant's Familiar

Flying, haste
Lieutenant — As long as you control your commander, this creature gets +2/+2 and has "Whenever this creature attacks, it deals 7 damage to target creature defending player controls."

Inferno Titan

{R}: This creature gets +1/+0 until end of turn.
Whenever this creature enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Sol Ring

Dragon Mage

Flying
Whenever this creature deals combat damage to a player, each player discards their hand, then draws seven cards.

Trumpeting Carnosaur

Trample
When this creature enters, discover 5.
{2}{R}, Discard this card: It deals 3 damage to target creature or planeswalker.

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.