This spell can't be countered.

You may have Altered Ego enter the battlefield as a copy of any creature on the battlefield, except it enters with X additional +1/+1 counters on it.

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.

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.

Whenever you cast a creature spell, draw a card.

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

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

{T}: Add {C}.

{3}{G}, {T}, Sacrifice Blighted Woodland: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

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

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.)

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.

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.

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

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

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

Exile target creature.

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}.

Dismal Backwater enters the battlefield tapped.

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

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

Choose one --

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

• Exile up to twice X target cards from graveyards.

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

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

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

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

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

Fertilid enters the battlefield with two +1/+1 counters on it.

{1}{G}, Remove a +1/+1 counter from Fertilid: Target player searches their library for a basic land card, puts it onto the battlefield tapped, then shuffles.

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.

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

({T}: Add {G}.)

Enchant creature

{U}: Tap enchanted creature.

{U}: Untap enchanted creature.

{T}: Add {G}.

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

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

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.

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.

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 Rot Farm enters the battlefield tapped.

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

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

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

Grakmaw, Skyclave Ravager enters the battlefield with three +1/+1 counters on it.

Whenever another creature you control dies, if it had a +1/+1 counter on it, put a +1/+1 counter on Grakmaw.

When Grakmaw dies, create an X/X black and green Hydra creature token, where X is the number of +1/+1 counters on Grakmaw.

Creatures you control with +1/+1 counters on them can't be blocked.

Heroes' Bane enters the battlefield with four +1/+1 counters on it.

{2}{G}{G}: Put X +1/+1 counters on Heroes' Bane, where X is its power.

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.)

Put a +1/+1 counter on target creature you control, then double the number of +1/+1 counters on that creature.

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

({T}: Add {U}.)

Jungle Hollow enters the battlefield tapped.

When Jungle Hollow enters the battlefield, you gain 1 life.

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

Whenever a creature with power 4 or greater enters the battlefield under your control, draw a card.

-1: Untap target permanent.

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.

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)

Destroy target artifact or enchantment.

At the beginning of your upkeep, scry 1.

Whenever you cast a creature spell, you may pay {G}. If you do, draw a card.

{T}: Add {C}.

{T}: Add {B} or {G}. Llanowar Wastes deals 1 damage to you.

Gain control of X target creatures and/or planeswalkers.

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

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

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.

Myriad Landscape enters the battlefield tapped.

{T}: Add {C}.

{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Flying

Nimbus Swimmer 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.

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."

Opulent Palace enters the battlefield tapped.

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

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.)

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Protean Hydra enters the battlefield 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.

Destroy target artifact or creature. It can't be regenerated.

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

When Reclamation Sage enters the battlefield, you may destroy target artifact or enchantment.

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

{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 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}.

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

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

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 {U} or {B}.)

Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

({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.

{T}: Add {C}{C}. Activate only if you control five or more lands.

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}.

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.

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.

Return X target cards from your graveyard to your hand. Exile Wildest Dreams.

Wildwood Scourge enters the battlefield 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 Wildwood Scourge.

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.