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.

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

Creatures you control have base power and toughness X/X until end of turn.

Draw four cards, then choose X cards in your hand and discard the rest.

Capricopian enters the battlefield 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.)

Castle Garenbrig enters the battlefield tapped unless you control a Forest.

{T}: Add {G}.

{2}{G}{G}, {T}: Add six {G}. Spend this mana only to cast creature spells or activate abilities of creatures.

Castle Locthwain enters the battlefield tapped unless you control a Swamp.

{T}: Add {B}.

{1}{B}{B}, {T}: Draw a card, then you lose life equal to the number of cards in your hand.

Castle Vantress enters the battlefield tapped unless you control an Island.

{T}: Add {U}.

{2}{U}{U}, {T}: Scry 2.

Counter target spell unless its controller pays {X}.

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

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 of your library and the rest on top in any order.)

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.

Target player draws X cards and loses X life.

Each player loses X life, discards X cards, sacrifices X creatures, then sacrifices X lands.

Destroy target creature. Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Dimir Aqueduct enters the battlefield tapped.

When Dimir Aqueduct enters the battlefield, return a land you control to its owner's hand.

{T}: Add {U}{B}.

Dimir Guildgate enters the battlefield tapped.

{T}: Add {U} or {B}.

Dismal Backwater enters the battlefield tapped.

When Dismal Backwater enters the battlefield, you gain 1 life.

{T}: Add {U} or {B}.

Gain control of target creature with mana value X or less.

Each player mills X cards. For each creature card put into a graveyard this way, you create a tapped 2/2 black Zombie creature token.

Search your library for up to three monocolored cards with different names and exile them. An opponent chooses one of those cards. Shuffle that card into your library. You may cast the other cards without paying their mana costs. Exile Emergent Ultimatum.

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

Gain control of target creature with mana value X.

Choose one --

• Target creature gets -X/-X until end of turn. You gain X life.

• Exile up to twice X target cards from graveyards.

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

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

Threshold -- If seven or more cards are in your graveyard, instead search your library for up to three basic land cards, put them onto the battlefield tapped, then shuffle.

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.

Destroy up to three target creatures with toughness X or less. If X is 10 or more, return all creature cards from your graveyard to the battlefield.

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

Foul Orchard enters the battlefield tapped.

{T}: Add {B} or {G}.

Populate X times. (To populate, create a token that's a copy of a creature token you control. Do this X times.)

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.

Destroy each nonland permanent with mana value X or less.

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.

Golgari Guildgate enters the battlefield tapped.

{T}: Add {B} or {G}.

Golgari Rot Farm enters tapped.

When Golgari Rot Farm enters, return a land you control to its owner's hand.

{T}: Add {B}{G}.

Tap X target nonland permanents.

Hangarback Walker enters with X +1/+1 counters on it.

When Hangarback Walker dies, create a 1/1 colorless Thopter artifact creature token with flying for each +1/+1 counter on Hangarback Walker.

{1}, {T}: Put a +1/+1 counter on Hangarback Walker.

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.

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.)

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.

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.

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

Jungle Hollow enters tapped.

When Jungle Hollow enters, you gain 1 life.

{T}: Add {B} or {G}.

{T}: Add {C}.

{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Destroy target creature with power X or less.

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

Gain control of X target creatures and/or planeswalkers.

Each opponent reveals cards from the top of their library until they reveal X land cards, then puts all cards revealed this way into their graveyard. X can't be 0.

Draw X cards.

This spell can't be countered.

Haste, protection from blue

Mistcutter Hydra enters the battlefield with X +1/+1 counters on it.

+2: Scry 2.

0: Look at the top card of your library. If it's a land card or a creature card with mana value less than or equal to the number of loyalty counters on Nissa, Steward of Elements, you may put that card onto the battlefield.

-6: Untap up to two target lands you control. They become 5/5 Elemental creatures with flying and haste until end of turn. They're still lands.

You may exile a green card with mana value X from your hand rather than pay this spell's mana cost.

You gain X life.

Opulent Palace enters the battlefield tapped.

{T}: Add {B}, {G}, or {U}.

Trample

Landfall -- Whenever a land enters the battlefield under your control, put a +1/+1 counter on Oran-Rief Hydra. If that land is a Forest, put two +1/+1 counters on Oran-Rief Hydra instead.

{T}: Add {C}{C}.

Polukranos enters the battlefield with six +1/+1 counters on it. It escapes with twelve +1/+1 counters on it instead.

If damage would be dealt to Polukranos while it has a +1/+1 counter on it, prevent that damage and remove that many +1/+1 counters from it.

{1}{B}{G}: Polukranos fights another target creature.

Escape--{4}{B}{G}, Exile six other cards from your graveyard.

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.)

Draw X cards, then discard a card.

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

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}.

Simic Guildgate enters the battlefield tapped.

{T}: Add {G} or {U}.

{T}: Add {C}{C}.

Return target creature with mana value X to its owner's hand. You create X 1/1 blue Faerie creature tokens with flying.

Reach, trample, protection from multicolored

Stonecoil Serpent enters the battlefield with X +1/+1 counters on it.

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)

Choose target creature, then choose another target creature for each time this spell was kicked. Put X +1/+1 counters on each of them.

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.

{T}: Add {B}, {G}, or {U}.

{B}{G}{U}, {T}, Sacrifice Sultai Banner: Draw a card.

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

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.

Temple of Deceit enters the battlefield tapped.

When Temple of Deceit enters the battlefield, scry 1.

{T}: Add {U} or {B}.

Temple of Malady enters tapped.

When Temple of Malady enters, scry 1.

{T}: Add {B} or {G}.

Temple of Mystery enters tapped.

When Temple of Mystery enters, scry 1.

{T}: Add {G} or {U}.

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}.

Thornwood Falls enters the battlefield tapped.

When Thornwood Falls enters the battlefield, you gain 1 life.

{T}: Add {G} or {U}.

Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent or discards a card.

{T}: Add {B}, {G}, or {U}.

Vastwood Hydra enters the battlefield with X +1/+1 counters on it.

When Vastwood Hydra dies, you may distribute a number of +1/+1 counters equal to the number of +1/+1 counters on Vastwood Hydra among any number of creatures you control.

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.

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.

Destroy all creatures with flying.

For any number of opponents, destroy target nonland permanent that player controls.

Woodland Stream enters the battlefield tapped.

{T}: Add {G} or {U}.

{T}: Add {B}, {G}, or {U}.

Cycling {2} ({2}, Discard this card: Draw a card.)

({T}: Add {B}, {G}, or {U}.)

Zagoth Triome enters the battlefield tapped.

Cycling {3} ({3}, Discard this card: Draw a card.)

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.