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.'"

Iron Myr

Kher Keep

{T}: Add {C}.
{1}{R}, {T}: Create a 0/1 red Kobold creature token named Kobolds of Kher Keep.

Treasonous Ogre

Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)
Pay 3 life: Add {R}.

Return the Favor

Spree (Choose one or more additional costs.)
+ {1} — Copy target instant spell, sorcery spell, activated ability, or triggered ability. You may choose new targets for the copy.
+ {1} — Change the target of target spell or ability with a single target.

Seize the Spoils

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

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Magnetic Theft

Attach target Equipment to target creature. (Control of the Equipment doesn't change.)

Cloud Key

As this artifact enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Tocasia's Dig Site

{T}: Add {C}.
{3}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Glittering Stockpile

{T}: Add {R}. Put a stash counter on this artifact.
{T}, Sacrifice this artifact: Add X mana of any one color, where X is the number of stash counters on this artifact.

Cryptic Trilobite

This creature enters with X +1/+1 counters on it.
Remove a +1/+1 counter from this creature: Add {C}{C}. Spend this mana only to activate abilities.
{1}, {T}: Put a +1/+1 counter on this creature.

The Mycosynth Gardens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{X}, {T}: This land becomes a copy of target nontoken artifact you control with mana value X.

Mountain

Thran Dynamo

Twinferno

Choose one —
• When you cast your next instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
• Target creature you control gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Twinflame

Strive — This spell costs {2}{R} more to cast for each target beyond the first.
Choose any number of target creatures you control. For each of them, create a token that's a copy of that creature, except it has haste. Exile those tokens at the beginning of the next end step.

Obliterating Bolt

Obliterating Bolt deals 4 damage to target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.

Ricochet Trap

If an opponent cast a blue spell this turn, you may pay {R} rather than pay this spell's mana cost.
Change the target of target spell with a single target.

Commune with Lava

Exile the top X cards of your library. Until the end of your next turn, you may play those cards.

Godo, Bandit Warlord

When Godo enters, you may search your library for an Equipment card, put it onto the battlefield, then shuffle.
Whenever Godo attacks for the first time each turn, untap it and all Samurai you control. After this phase, there is an additional combat phase.

Welding Jar

Sacrifice this artifact: Regenerate target artifact.

Field of Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.

Witchstalker Frenzy

This spell costs {1} less to cast for each creature that attacked this turn.
Witchstalker Frenzy deals 5 damage to target creature.

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Return target artifact card from your graveyard to your hand.

Trash for Treasure

As an additional cost to cast this spell, sacrifice an artifact.
Return target artifact card from your graveyard to the battlefield.

Gilded Lotus

Irencrag Feat

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

Mana Seism

Sacrifice any number of lands, then add that much {C}.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
This artifact enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on this artifact.

Arcane Signet

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

Soulbright Flamekin

{2}: Target creature gains trample until end of turn. If this is the third time this ability has resolved this turn, you may add {R}{R}{R}{R}{R}{R}{R}{R}.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Generator Servant

{T}, Sacrifice this creature: Add {C}{C}. If that mana is spent on a creature spell, it gains haste until end of turn. (That creature can attack and {T} as soon as it comes under your control.)

Simian Spirit Guide

Geosurge

Add {R}{R}{R}{R}{R}{R}{R}. Spend this mana only to cast artifact or creature spells.

Basalt Monolith

This artifact doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{3}: Untap this artifact.

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Pirate's Pillage

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.")

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Mind Stone

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

Glimpse the Impossible

Exile the top three cards of your library. You may play those cards this turn. At the beginning of the next end step, if any of those cards remain exiled, put them into your graveyard, then create a 0/1 colorless Eldrazi Spawn creature token for each card put into your graveyard this way. Those tokens have "Sacrifice this token: Add {C}."

Cursed Mirror

{T}: Add {R}.
As this artifact enters, you may have it become a copy of any creature on the battlefield until end of turn, except it has haste.

Daretti, Scrap Savant

+2: Discard up to two cards, then draw that many cards.
−2: Sacrifice an artifact. If you do, return target artifact card from your graveyard to the battlefield.
−10: You get an emblem with "Whenever an artifact is put into your graveyard from the battlefield, return that card to the battlefield at the beginning of the next end step."
Daretti, Scrap Savant can be your commander.

Palladium Myr

Dualcaster Mage

Flash
When this creature enters, copy target instant or sorcery spell. You may choose new targets for the copy.

Runaway Steam-Kin

Whenever you cast a red spell, if this creature has fewer than three +1/+1 counters on it, put a +1/+1 counter on this creature.
Remove three +1/+1 counters from this creature: Add {R}{R}{R}.

Manakin

Brass Squire

{T}: Attach target Equipment you control to target creature you control.

Hedron Crawler

{T}: Add {C}. ({C} represents colorless mana.)

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

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.

Seething Song

Dwarven Ruins

This land enters tapped.
{T}: Add {R}.
{T}, Sacrifice this land: Add {R}{R}.

Sandstone Needle

This land enters tapped with two depletion counters on it.
{T}, Remove a depletion counter from this land: Add {R}{R}. If there are no depletion counters on this land, sacrifice it.

Chandra, Novice Pyromancer

+1: Elementals you control get +2/+0 until end of turn.
−1: Add {R}{R}.
−2: Chandra deals 2 damage to any target.

Vessel of Volatility

{1}{R}, Sacrifice this enchantment: Add {R}{R}{R}{R}.

Worn Powerstone

This artifact enters tapped.
{T}: Add {C}{C}.

Zoyowa's Justice

The owner of target artifact or creature with mana value 1 or greater shuffles it into their library. Then that player discovers X, where X is its mana value. (They exile cards from the top of their library until they exile a nonland card with that mana value or less. They cast it without paying its mana cost or put it into their hand. They put the rest on the bottom in a random order.)

_____ Goblin

When this creature enters, you may put a name sticker on it. Add {R} for each unique vowel on that sticker. (The vowels are A, E, I, O, U, and Y.)

Chain Reaction

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

Reckless Barbarian

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Grinning Ignus

{R}, Return this creature to its owner's hand: Add {C}{C}{R}. Activate only as a sorcery.

Hammer of Nazahn

Whenever Hammer of Nazahn or another Equipment you control enters, you may attach that Equipment to target creature you control.
Equipped creature gets +2/+0 and has indestructible.
Equip {4}

Big Score

Defense Grid

Each spell costs {3} more to cast except during its controller's turn.

Excavation Explosion

Excavation Explosion deals 3 damage to any target. Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Winter Moon

Players can't untap more than one nonbasic land during their untap steps.

Sol Ring

The Eternity Elevator

{T}: Add {C}{C}{C}.
Station (Tap another creature you control: Put charge counters equal to its power on this Spacecraft. Station only as a sorcery.)
20+ | {T}: Add X mana of any one color, where X is the number of charge counters on The Eternity Elevator.

Gone

Return target creature you don't control to its owner's hand.

Dead

Dead // Gone

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Strike It Rich

Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)