Skeletal Scrying

As an additional cost to cast this spell, exile X cards from your graveyard.
You draw X cards and you lose X life.

Stream of Life

Multiple Choice

If X is 1, scry 1, then draw a card.
If X is 2, you may choose a player. They return a creature they control to its owner's hand.
If X is 3, create a 4/4 blue and red Elemental creature token.
If X is 4 or more, do all of the above.

Suffer the Past

Exile X target cards from target player's graveyard. For each card exiled this way, that player loses 1 life and you gain 1 life.

Black Sun's Twilight

Up to one target creature gets -X/-X until end of turn. If X is 5 or more, return a creature card with mana value X or less from your graveyard to the battlefield tapped.

Icy Blast

Tap X target creatures.
Ferocious — If you control a creature with power 4 or greater, those creatures don't untap during their controllers' next untap steps.

Gang Up

Assist (Another player can pay up to {X} of this spell's cost. You choose the value of X.)
Destroy target creature with power X or less.

Corrosive Gale

({G/P} can be paid with either {G} or 2 life.)
Corrosive Gale deals X damage to each creature with flying.

Condescend

Counter target spell unless its controller pays {X}. Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Death Wind

Target creature gets -X/-X until end of turn.

Increasing Confusion

Target player mills X cards. If this spell was cast from a graveyard, that player mills twice that many cards instead.
Flashback {X}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Stir the Grave

Return target creature card with mana value X or less from your graveyard to the battlefield.

Capricopian

Capricopian enters with X +1/+1 counters on it.
{2}: Put a +1/+1 counter on Capricopian, then you may reselect which player Capricopian is attacking. Only the player Capricopian is attacking may activate this ability and only during the declare attackers step. (It can't attack its controller.)

Tropical Storm

Tropical Storm deals X damage to each creature with flying and 1 additional damage to each blue creature.

Wren's Run Hydra

Reach
Wren's Run Hydra enters with X +1/+1 counters on it.
Reinforce X—{X}{G}{G} ({X}{G}{G}, Discard this card: Put X +1/+1 counters on target creature.)

Untamed Might

Target creature gets +X/+X until end of turn.

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.

Broken Ambitions

Counter target spell unless its controller pays {X}. Clash with an opponent. If you win, that spell's controller mills four cards. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Sigil of Distinction

Sigil of Distinction enters with X charge counters on it.
Equipped creature gets +1/+1 for each charge counter on Sigil of Distinction.
Equip—Remove a charge counter from Sigil of Distinction.

Haldir, Lórien Lieutenant

Haldir, Lórien Lieutenant enters with X +1/+1 counters on it.
Vigilance
{5}{G}: Until end of turn, other Elves you control gain vigilance and get +1/+1 for each +1/+1 counter on Haldir.

The Crowd Goes Wild

Assist (Another player can pay up to {X} of this spell's cost. You choose the value of X.)
Support X. (Put a +1/+1 counter on each of up to X target creatures.)
Each creature with a +1/+1 counter on it gains trample until end of turn.

Postmortem Lunge

({B/P} can be paid with either {B} or 2 life.)
Return target creature card with mana value X from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step.

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.

Sphere of Annihilation

Sphere of Annihilation enters with X void counters on it.
At the beginning of your upkeep, exile Sphere of Annihilation, all creatures and planeswalkers with mana value less than or equal to the number of void counters on it, and all creature and planeswalker cards in graveyards with mana value less than or equal to the number of void counters on it.

Feral Hydra

Feral Hydra enters with X +1/+1 counters on it.
{3}: Put a +1/+1 counter on Feral Hydra. Any player may activate this ability.

Confront the Past

Choose one —
• Return target planeswalker card with mana value X or less from your graveyard to the battlefield.
• Remove twice X loyalty counters from target planeswalker an opponent controls.

Phyrexian Marauder

Phyrexian Marauder enters with X +1/+1 counters on it.
Phyrexian Marauder can't block.
Phyrexian Marauder can't attack unless you pay {1} for each +1/+1 counter on it.

Thrive

Put a +1/+1 counter on each of X target creatures.

Seer's Vision

Your opponents play with their hands revealed.
Sacrifice Seer's Vision: Look at target player's hand and choose a card from it. That player discards that card. Activate only as a sorcery.

Wildwood Scourge

This creature enters with X +1/+1 counters on it.
Whenever one or more +1/+1 counters are put on another non-Hydra creature you control, put a +1/+1 counter on this creature.

Sporocyst

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Defender
Spore Chimney — When Sporocyst enters, search your library for up to X basic land cards, put them onto the battlefield tapped, then shuffle.

Sylvan Offering

Choose an opponent. You and that player each create an X/X green Treefolk creature token.
Choose an opponent. You and that player each create X 1/1 green Elf Warrior creature tokens.

Engineered Explosives

Sunburst (This enters with a charge counter on it for each color of mana spent to cast it.)
{2}, Sacrifice Engineered Explosives: Destroy each nonland permanent with mana value equal to the number of charge counters on Engineered Explosives.

Shifting Wall

Defender (This creature can't attack.)
Shifting Wall enters with X +1/+1 counters on it.

Green Sun's Twilight

Reveal the top X plus one cards of your library. Choose a creature card and/or a land card from among them. Put those cards into your hand and the rest on the bottom of your library in a random order. If X is 5 or more, instead put the chosen cards onto the battlefield or into your hand and the rest on the bottom of your library in a random order.

Aether Tide

As an additional cost to cast this spell, discard X creature cards.
Return X target creatures to their owners' hands.

Liliana's Indignation

Mill X cards. Target player loses 2 life for each creature card put into your graveyard this way.

Mind Twist

Target player discards X cards at random.

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.

Primal Might

Target creature you control gets +X/+X until end of turn. Then it fights up to one target creature you don't control. (Each deals damage equal to its power to the other.)

Protean Hydra

Protean Hydra enters with X +1/+1 counters on it.
If damage would be dealt to Protean Hydra, prevent that damage and remove that many +1/+1 counters from it.
Whenever a +1/+1 counter is removed from Protean Hydra, put two +1/+1 counters on it at the beginning of the next end step.

Spell Blast

Counter target spell with mana value X. (For example, if that spell's mana cost is {3}{U}{U}, X is 5.)

Battle at the Bridge

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Target creature gets -X/-X until end of turn. You gain X life.

Choking Vines

Cast this spell only during the declare blockers step.
X target attacking creatures become blocked. Choking Vines deals 1 damage to each of those creatures. (This spell works on creatures that can't be blocked.)

March of Swirling Mist

As an additional cost to cast this spell, you may exile any number of blue cards from your hand. This spell costs {2} less to cast for each card exiled this way.
Up to X target creatures phase out. (While they're phased out, they're treated as though they don't exist. Each one phases in before its controller untaps during their next untap step.)

Repeal

Return target nonland permanent with mana value X to its owner's hand.
Draw a card.

Molder

Destroy target artifact or enchantment with mana value X. It can't be regenerated. You gain X life.

Silkguard

Put a +1/+1 counter on each of up to X target creatures you control.
Auras, Equipment, and modified creatures you control gain hexproof until end of turn. (Equipment, Auras you control, and counters are modifications.)

Endless Scream

Enchant creature
Endless Scream enters with X scream counters on it.
Enchanted creature gets +1/+0 for each scream counter on Endless Scream.

Winter Blast

Tap X target creatures. Winter Blast deals 2 damage to each of those creatures with flying.

Wandering Eye

Flying
Players play with their hands revealed.

Termagant Swarm

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Death Frenzy — When Termagant Swarm dies, create a number of 1/1 green Tyranid creature tokens equal to Termagant Swarm's power.

Mana Bloom

Mana Bloom enters with X charge counters on it.
Remove a charge counter from Mana Bloom: Add one mana of any color. Activate only once each turn.
At the beginning of your upkeep, if Mana Bloom has no charge counters on it, return it to its owner's hand.

Zur's Weirding

Players play with their hands revealed.
If a player would draw a card, they reveal it instead. Then any other player may pay 2 life. If a player does, put that card into its owner's graveyard. Otherwise, that player draws a card.

Stonecoil Serpent

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

Serene Sunset

Prevent all combat damage X target creatures would deal this turn.

Prosperity

Wurmcalling

Buyback {2}{G} (You may pay an additional {2}{G} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create an X/X green Wurm creature token.

Knickknack Ouphe

Knickknack Ouphe enters with X +1/+1 counters on it.
When Knickknack Ouphe enters, reveal the top X cards of your library. You may put any number of Aura cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield on the bottom of your library in a random order.

Ivy Elemental

Ivy Elemental enters with X +1/+1 counters on it.

Gridlock

Killing Wave

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

Selective Snare

Return X target creatures of the creature type of your choice to their owner's hand.

Winter's Chill

Cast this spell only during combat before blockers are declared.
X can't be greater than the number of snow lands you control.
Choose X target attacking creatures. For each of those creatures, its controller may pay {1} or {2}. If that player doesn't, destroy that creature at end of combat. If that player pays only {1}, prevent all combat damage that would be dealt to and dealt by that creature this combat.

Soul Strings

Return two target creature cards from your graveyard to your hand unless any player pays {X}.

Clown Car

When Clown Car enters, roll X six-sided dice. For each odd result, create a 1/1 white Clown Robot artifact creature token. For each even result, put a +1/+1 counter on Clown Car.
Crew 2

Howl from Beyond

Target creature gets +X/+0 until end of turn.

Enshrined Memories

Reveal the top X cards of your library. Put all creature cards revealed this way into your hand and the rest on the bottom of your library in any order.

Erebos's Intervention

Choose one —
• Target creature gets -X/-X until end of turn. You gain X life.
• Exile up to twice X target cards from graveyards.

March of Wretched Sorrow

As an additional cost to cast this spell, you may exile any number of black cards from your hand. This spell costs {2} less to cast for each card exiled this way.
March of Wretched Sorrow deals X damage to target creature or planeswalker and you gain X life.

Syncopate

Counter target spell unless its controller pays {X}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Briber's Purse

Briber's Purse enters with X gem counters on it.
{1}, {T}, Remove a gem counter from Briber's Purse: Target creature can't attack or block this turn.

Occult Epiphany

Draw X cards, then discard X cards. Create a 1/1 white Spirit creature token with flying for each card type among cards discarded this way.

Contortionist Troupe

Contortionist Troupe enters with X +1/+1 counters on it.
Coven — At the beginning of your end step, if you control three or more creatures with different powers, put a +1/+1 counter on target creature you control.

Telepathy

Your opponents play with their hands revealed.

Slime Molding

Ochre Jelly

Trample
Ochre Jelly enters with X +1/+1 counters on it.
Split — When Ochre Jelly dies, if it had two or more +1/+1 counters on it, create a token that's a copy of it at the beginning of the next end step. The token enters with half that many +1/+1 counters on it, rounded down.

Endless One

Endless One enters with X +1/+1 counters on it.

Spoils of War

X is the number of artifact and/or creature cards in an opponent's graveyard as you cast this spell.
Distribute X +1/+1 counters among any number of target creatures.

Killing Glare

Destroy target creature with power X or less.

Rats' Feast

Exile X target cards from a single graveyard.

Bond of Agony

As an additional cost to cast this spell, pay X life.
Each other player loses X life.

Power Sink

Counter target spell unless its controller pays {X}. If that player doesn't, they tap all lands with mana abilities they control and lose all unspent mana.

Ugin's Conjurant

Ugin's Conjurant enters with X +1/+1 counters on it.
If damage would be dealt to Ugin's Conjurant while it has a +1/+1 counter on it, prevent that damage and remove that many +1/+1 counters from Ugin's Conjurant.

Spell Burst

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Counter target spell with mana value X.

Hungering Hydra

Hungering Hydra enters 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.)

Mistcutter Hydra

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

Revelation

Luxurious Libation

Target creature gets +X/+X until end of turn. Create a 1/1 green and white Citizen creature token.

Faerie Fencing

Target creature gets -X/-X until end of turn. That creature gets an additional -3/-3 until end of turn if you controlled a Faerie as you cast this spell.

Disembowel

Destroy target creature with mana value X.

Venarian Glimmer

Target player reveals their hand. You choose a nonland card with mana value X or less from it. That player discards that card.

Chimeric Mass

Chimeric Mass enters with X charge counters on it.
{1}: Until end of turn, Chimeric Mass becomes a Construct artifact creature with "This creature's power and toughness are each equal to the number of charge counters on it."

Ingenious Prodigy

Skulk (This creature can't be blocked by creatures with greater power.)
Ingenious Prodigy enters with X +1/+1 counters on it.
At the beginning of your upkeep, if Ingenious Prodigy has one or more +1/+1 counters on it, you may remove a +1/+1 counter from it. If you do, draw a card.

Hurricane

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

Lifecraft Awakening

Put X +1/+1 counters on target artifact you control. If it isn't a creature or Vehicle, it becomes a 0/0 Construct artifact creature.

Ertai's Meddling

X can't be 0.
Target spell's controller exiles it with X delay counters on it.
At the beginning of each of that player's upkeeps, if that card is exiled, remove a delay counter from it. If the card has no delay counters on it, the player puts it onto the stack as a copy of the original spell.

Clash of Wills

Counter target spell unless its controller pays {X}.

Read the Runes

Draw X cards. For each card drawn this way, discard a card unless you sacrifice a permanent.

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.)

Windstorm

Windstorm deals X damage to each creature with flying.

March of Burgeoning Life

As an additional cost to cast this spell, you may exile any number of green cards from your hand. This spell costs {2} less to cast for each card exiled this way.
Choose target creature with mana value less than X. Search your library for a creature card with the same name as that creature, put it onto the battlefield tapped, then shuffle.

Bloodcurdling Scream

Hormagaunt Horde

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Endless Swarm — Whenever a land you control enters, you may pay {2}{G}. If you do, return Hormagaunt Horde from your graveyard to your hand.