Unbound Flourishing

Whenever you cast a permanent spell with a mana cost that contains {X}, double the value of X.
Whenever you cast an instant or sorcery spell or activate an ability, if that spell's mana cost or that ability's activation cost contains {X}, copy that spell or ability. You may choose new targets for the copy.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Verdant Sun's Avatar

Whenever Verdant Sun's Avatar or another creature enters the battlefield under your control, you gain life equal to that creature's toughness.

Stonecoil Serpent

Reach, trample, protection from multicolored
Stonecoil Serpent enters the battlefield with X +1/+1 counters on it.

Mistcutter Hydra

This spell can't be countered.
Haste, protection from blue
Mistcutter Hydra enters the battlefield with X +1/+1 counters on it.

Ohran Frostfang

Attacking creatures you control have deathtouch.
Whenever a creature you control deals combat damage to a player, draw a card.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Garruk's Uprising

When Garruk's Uprising enters the battlefield, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample. (They can deal excess combat damage to the player or planeswalker they're attacking.)
Whenever a creature with power 4 or greater enters the battlefield under your control, draw a card.

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Tangled Islet

({T}: Add {G} or {U}.)
Tangled Islet enters the battlefield tapped.

Barad-dûr

Barad-dûr enters the battlefield tapped unless you control a legendary creature.
{T}: Add {B}.
{X}{X}{B}, {T}: Amass Orcs X. Activate only if a creature died this turn.

Silver Scrutiny

You may cast Silver Scrutiny as though it had flash if X is 3 or less.
Draw X cards.

Command Tower

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

Corpsejack Menace

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on it instead.

Curse of the Swine

Exile X target creatures. For each creature exiled this way, its controller creates a 2/2 green Boar creature token.

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Farseek

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

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Kodama's Reach

Choked Estuary

As Choked Estuary enters the battlefield, you may reveal an Island or Swamp card from your hand. If you don't, Choked Estuary enters the battlefield tapped.
{T}: Add {U} or {B}.

Damnable Pact

Target player draws X cards and loses X life.

Genesis Hydra

When you cast this spell, reveal the top X cards of your library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield. Then shuffle the rest into your library.
Genesis Hydra enters the battlefield with X +1/+1 counters on it.

Shipwreck Marsh

Shipwreck Marsh enters the battlefield tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Muldrotha, the Gravetide

During each of your turns, you may play a land and cast a permanent spell of each permanent type from your graveyard. (If a card has multiple permanent types, choose one as you play it.)

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. Yavimaya Coast deals 1 damage to you.

Darkslick Shores

Darkslick Shores enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {U} or {B}.

Killing Wave

For each creature, its controller sacrifices it unless they pay X life.

Island

Green Sun's Zenith

Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.

Villainous Wealth

Target opponent exiles the top X cards of their library. You may cast any number of spells with mana value X or less from among them without paying their mana costs.

Profane Command

Choose two —
• Target player loses X life.
• Return target creature card with mana value X or less from your graveyard to the battlefield.
• Target creature gets -X/-X until end of turn.
• Up to X target creatures gain fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)

Great Hall of the Citadel

{T}: Add {C}.
{1}, {T}: Add two mana in any combination of colors. Spend this mana only to cast legendary spells.

Opulent Palace

Opulent Palace enters the battlefield tapped.
{T}: Add {B}, {G}, or {U}.

Freed from the Real

Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.

Primordial Hydra

Primordial Hydra enters the battlefield with X +1/+1 counters on it.
At the beginning of your upkeep, double the number of +1/+1 counters on Primordial Hydra.
Primordial Hydra has trample as long as it has ten or more +1/+1 counters on it.

Jarad, Golgari Lich Lord

Jarad, Golgari Lich Lord gets +1/+1 for each creature card in your graveyard.
{1}{B}{G}, Sacrifice another creature: Each opponent loses life equal to the sacrificed creature's power.
Sacrifice a Swamp and a Forest: Return Jarad from your graveyard to your hand.

Lair of the Hydra

If you control two or more other lands, Lair of the Hydra enters the battlefield tapped.
{T}: Add {G}.
{X}{G}: Until end of turn, Lair of the Hydra becomes an X/X green Hydra creature. It's still a land. X can't be 0.

Mind Spring

Inga and Esika

Creatures you control have vigilance and "{T}: Add one mana of any color. Spend this mana only to cast a creature spell."
Whenever you cast a creature spell, if three or more mana from creatures was spent to cast it, draw a card.

Fellwar Stone

Tervigon

Ravenous (This creature enters the battlefield with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Trample
Spawn Termagants — Whenever Tervigon deals combat damage to a player, create that many 1/1 green Tyranid creature tokens.

Sol Ring

Zaxara, the Exemplary

Deathtouch
{T}: Add two mana of any one color.
Whenever you cast a spell with {X} in its mana cost, create a 0/0 green Hydra creature token, then put X +1/+1 counters on it.

Voracious Hydra

Trample
Voracious Hydra enters the battlefield with X +1/+1 counters on it.
When Voracious Hydra enters the battlefield, choose one —
• Double the number of +1/+1 counters on Voracious Hydra.
• Voracious Hydra fights target creature you don't control.

Temple of Malady

Temple of Malady enters the battlefield tapped.
When Temple of Malady enters the battlefield, scry 1.
{T}: Add {B} or {G}.

Shire Terrace

{T}: Add {C}.
{1}, {T}, Sacrifice Shire Terrace: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Zilortha, Apex of Ikoria

Reach
For each non-Human creature you control, you may have that creature assign its combat damage as though it weren't blocked.

Invasion of Ikoria

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Ikoria enters the battlefield, search your library and/or graveyard for a non-Human creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle.

Invasion of Ikoria // Zilortha, Apex of Ikoria

Forest

Neverwinter Hydra

As Neverwinter Hydra enters the battlefield, roll X d6. It enters with a number of +1/+1 counters on it equal to the total of those results.
Trample
Ward {4} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.)

Thassa's Intervention

Choose one —
• Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.
• Counter target spell unless its controller pays twice {X}.

Squall Line

Squall Line deals X damage to each creature with flying and each player.

Animist's Awakening

Reveal the top X cards of your library. Put all land cards from among them onto the battlefield tapped and the rest on the bottom of your library in a random order.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, untap those lands.

The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on Forgotten Ancient.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures.

Uncage the Menagerie

Search your library for up to X creature cards with different names that each have mana value X, reveal them, put them into your hand, then shuffle.

Swamp

Simic Ascendancy

{1}{G}{U}: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on Simic Ascendancy.
At the beginning of your upkeep, if Simic Ascendancy has twenty or more growth counters on it, you win the game.

Simic Growth Chamber

Simic Growth Chamber enters the battlefield tapped.
When Simic Growth Chamber enters the battlefield, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Ancient Bronze Dragon

Flying
Whenever Ancient Bronze Dragon deals combat damage to a player, roll a d20. When you do, put X +1/+1 counters on each of up to two target creatures, where X is the result.

Hurricane

Hurricane deals X damage to each creature with flying and each player.

Kalonian Hydra

Trample
Kalonian Hydra enters the battlefield with four +1/+1 counters on it.
Whenever Kalonian Hydra attacks, double the number of +1/+1 counters on each creature you control.

Whiptongue Hydra

Reach
When Whiptongue Hydra enters the battlefield, destroy all creatures with flying. Put a +1/+1 counter on Whiptongue Hydra for each creature destroyed this way.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Blue Sun's Twilight

Gain control of target creature with mana value X or less. If X is 5 or more, create a token that's a copy of that creature.

Hungering Hydra

Hungering Hydra enters the battlefield with X +1/+1 counters on it.
Hungering Hydra can't be blocked by more than one creature.
Whenever Hungering Hydra is dealt damage, put that many +1/+1 counters on it. (It must survive the damage to get the counters.)

Body of Research

Create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is the number of cards in your library.

Gargos, Vicious Watcher

Vigilance
Hydra spells you cast cost {4} less to cast.
Whenever a creature you control becomes the target of a spell, Gargos, Vicious Watcher fights up to one target creature you don't control.

Esix, Fractal Bloom

Flying
The first time you would create one or more tokens during each of your turns, you may instead choose a creature other than Esix, Fractal Bloom and create that many tokens that are copies of that creature.

Vorinclex, Monstrous Raider

Trample, haste
If you would put one or more counters on a permanent or player, put twice that many of each of those kinds of counters on that permanent or player instead.
If an opponent would put one or more counters on a permanent or player, they put half that many of each of those kinds of counters on that permanent or player instead, rounded down.

Tyvar's Stand

Target creature you control gets +X/+X and gains hexproof and indestructible until end of turn. (A creature with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Silundi Isle

Silundi Isle enters the battlefield tapped.
{T}: Add {U}.

Silundi Vision

Look at the top six cards of your library. You may reveal an instant or sorcery card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Silundi Vision // Silundi Isle

Lumbering Falls

Lumbering Falls enters the battlefield tapped.
{T}: Add {G} or {U}.
{2}{G}{U}: Lumbering Falls becomes a 3/3 green and blue Elemental creature with hexproof until end of turn. It's still a land.

Temple of Mystery

Temple of Mystery enters the battlefield tapped.
When Temple of Mystery enters the battlefield, scry 1.
{T}: Add {G} or {U}.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Steelbane Hydra

Steelbane Hydra enters the battlefield with X +1/+1 counters on it.
{2}{G}, Remove a +1/+1 counter from Steelbane Hydra: Destroy target artifact or enchantment.

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Morphic Pool

Morphic Pool enters the battlefield tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Yarok, the Desecrated

Deathtouch, lifelink
If a permanent entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Fractal Harness

When Fractal Harness enters the battlefield, create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it and attach Fractal Harness to it.
Whenever equipped creature attacks, double the number of +1/+1 counters on it.
Equip {2}

Elementalist's Palette

Whenever you cast a spell with {X} in its mana cost, put two charge counters on Elementalist's Palette.
{T}: Add one mana of any color.
{T}: Add {C} for each charge counter on Elementalist's Palette. Spend this mana only on costs that contain {X}.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Kruphix, God of Horizons

Indestructible
As long as your devotion to green and blue is less than seven, Kruphix isn't a creature.
You have no maximum hand size.
If you would lose unspent mana, that mana becomes colorless instead.

Haunted Mire

({T}: Add {B} or {G}.)
Haunted Mire enters the battlefield tapped.

Hooded Hydra

Hooded Hydra enters the battlefield with X +1/+1 counters on it.
When Hooded Hydra dies, create a 1/1 green Snake creature token for each +1/+1 counter on it.
Morph {3}{G}{G}
As Hooded Hydra is turned face up, put five +1/+1 counters on it.

Somberwald Sage

{T}: Add three mana of any one color. Spend this mana only to cast creature spells.

Open into Wonder

X target creatures can't be blocked this turn. Until end of turn, those creatures gain "Whenever this creature deals combat damage to a player, draw a card."

Hinterland Harbor

Hinterland Harbor enters the battlefield tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Arcane Signet

Hydroid Krasis

When you cast this spell, you gain half X life and draw half X cards. Round down each time.
Flying, trample
Hydroid Krasis enters the battlefield with X +1/+1 counters on it.