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.

Arixmethes, Slumbering Isle enters the battlefield tapped with five slumber counters on it.

As long as Arixmethes has a slumber counter on it, it's a land. (It's not a creature.)

Whenever you cast a spell, you may remove a slumber counter from Arixmethes.

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

Astral Cornucopia enters the battlefield with X charge counters on it.

{T}: Choose a color. Add one mana of that color for each charge counter on Astral Cornucopia.

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

Flying

{T}: Add one mana of any color.

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

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

As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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.)

{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.)

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

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

Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Target player draws X cards and loses X life.

If you control a commander, you may cast this spell without paying its mana cost.

Exile target creature.

Search your library for a card, put that card into your hand, then shuffle.

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

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

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

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

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

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

If you control a commander, you may cast this spell without paying its mana cost.

Counter target noncreature spell.

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.

Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.

Exile Finale of Revelation.

If it's not your turn, you may exile a blue card from your hand rather than pay this spell's mana cost.

Counter target noncreature spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

({T}: Add {G}.)

Enchant creature

{U}: Tap enchanted creature.

{U}: Untap enchanted creature.

When Gadwick, the Wizened enters the battlefield, draw X cards.

Whenever you cast a blue spell, tap target nonland permanent an opponent controls.

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

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Draw a card. You may put a land card from your hand onto the battlefield.

Whenever a nontoken creature enters the battlefield under your control, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Permanents you control gain hexproof and indestructible until end of turn.

{X}{X}{G}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)

When Hydra Broodmaster becomes monstrous, create X X/X green Hydra creature tokens.

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.

({T}: Add {U}.)

Whenever you tap a nonland permanent for mana, add one mana of any type that permanent produced.

{5}{G}{U}: Look at the top five cards of your library. You may put a non-Human creature card from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Trample

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

When Lifeblood Hydra dies, you gain life and draw cards equal to its power.

{T}: Add {G}.

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.

This spell can't be countered.

Haste, protection from blue

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

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Morphic Pool enters the battlefield tapped unless you have two or more opponents.

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

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Whenever you tap a Forest for mana, add an additional {G}.

+1: Put three +1/+1 counters on up to one target noncreature land you control. Untap it. It becomes a 0/0 Elemental creature with vigilance and haste that's still a land.

-8: You get an emblem with "Lands you control have indestructible." Search your library for any number of Forest cards, put them onto the battlefield tapped, then shuffle.

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."

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

As Overgrown Tomb enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Enchant creature

{U}: Untap enchanted creature.

{U}: Enchanted creature gains flying until end of turn.

{U}: Enchanted creature gains shroud until end of turn. (It can't be the target of spells or abilities.)

{1}: Enchanted creature gets +1/-1 or -1/+1 until end of turn.

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

{X}{X}{G}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)

When Polukranos, World Eater becomes monstrous, it deals X damage divided as you choose among any number of target creatures your opponents control. Each of those creatures deals damage equal to its power to Polukranos.

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.

{T}, Pay 1 life, Sacrifice Prismatic Vista: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Draw X cards, then discard a card.

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

{1}, {T}: Add {G}{U}.

({T}: Add {G}.)

({T}: Add {U}.)

({T}: Add {B}.)

When Spellseeker enters the battlefield, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

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.

Reach, trample, protection from multicolored

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

({T}: Add {B}.)

At the beginning of your draw step, you may draw two additional cards. If you do, choose two cards in your hand drawn this turn. For each of those cards, pay 4 life or put the card on top of your library.

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.

This spell costs {X} less to cast, where X is the greatest power among creatures you control.

{T}: Add {G}{G}. You gain 2 life.

Whenever a nontoken creature enters the battlefield under your control, put a +1/+1 counter on it and draw a card.

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

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

Reach

Ulvenwald Hydra's power and toughness are each equal to the number of lands you control.

When Ulvenwald Hydra enters the battlefield, you may search your library for a land card, put it onto the battlefield tapped, then shuffle.

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.

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

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

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.

{T}, Pay 1 life, Sacrifice Verdant Catacombs: Search your library for a Swamp or Forest card, put it onto the battlefield, then shuffle.

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.

Walking Ballista enters with X +1/+1 counters on it.

{4}: Put a +1/+1 counter on Walking Ballista.

Remove a +1/+1 counter from Walking Ballista: It deals 1 damage to any target.

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

As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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.