Kalonian Hydra

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

Ulvenwald Hydra

Reach
Ulvenwald Hydra's power and toughness are each equal to the number of lands you control.
When Ulvenwald Hydra enters, you may search your library for a land card, put it onto the battlefield tapped, then shuffle.

Honored Hydra

Trample
Embalm {3}{G} ({3}{G}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Snake Hydra with no mana cost. Embalm only as a sorcery.)

Phytohydra

If damage would be dealt to Phytohydra, put that many +1/+1 counters on it instead.

Magus Lucea Kane

Spiritual Leader — At the beginning of combat on your turn, put a +1/+1 counter on target creature.
Psychic Stimulus — {T}: Add {C}{C}. When you next cast a spell with {X} in its mana cost or activate an ability with {X} in its activation cost this turn, copy that spell or ability. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

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.)

Hooded Hydra

Hooded Hydra enters 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.

Abundant Growth

Enchant land
When Abundant Growth enters, draw a card.
Enchanted land has "{T}: Add one mana of any color."

Neverwinter Hydra

As Neverwinter Hydra enters, 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}.)

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.

Clamavus

Proclamator Hailer — Each creature you control gets +1/+1 for each +1/+1 counter on it.

Rampant Growth

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

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.

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on Managorger Hydra.

Bristling Hydra

When Bristling Hydra enters, you get {E}{E}{E} (three energy counters).
Pay {E}{E}{E}: Put a +1/+1 counter on Bristling Hydra. It gains hexproof until end of turn.

Oran-Rief Hydra

Trample
Landfall — Whenever a land you control enters, 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.

Nissa, Who Shakes the World

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.

Rampant Rejuvenator

Rampant Rejuvenator enters with two +1/+1 counters on it.
When Rampant Rejuvenator dies, search your library for up to X basic land cards, where X is Rampant Rejuvenator's power, put them onto the battlefield, then shuffle.

Divergent Growth

Until end of turn, lands you control gain "{T}: Add one mana of any color."

Heroes' Bane

This creature enters with four +1/+1 counters on it.
{2}{G}{G}: Put X +1/+1 counters on this creature, where X is its power.

Stumpsquall Hydra

When Stumpsquall Hydra enters, distribute X +1/+1 counters among it and any number of commanders.

Ramunap Hydra

Vigilance, reach, trample
Ramunap Hydra gets +1/+1 as long as you control a Desert.
Ramunap Hydra gets +1/+1 as long as there is a Desert card in your graveyard.

Shivan Devastator

Flying, haste
Shivan Devastator enters with X +1/+1 counters on it.

Gyrus, Waker of Corpses

Gyrus, Waker of Corpses enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
Whenever Gyrus attacks, you may exile target creature card with lesser power from your graveyard. If you do, create a token that's a copy of that card and that's tapped and attacking. Exile the token at end of combat.

Lifeblood Hydra

Trample
Lifeblood Hydra enters with X +1/+1 counters on it.
When Lifeblood Hydra dies, you gain life and draw cards equal to its power.

Molten Hydra

{1}{R}{R}: Put a +1/+1 counter on Molten Hydra.
{T}, Remove all +1/+1 counters from Molten Hydra: It deals damage to any target equal to the number of +1/+1 counters removed this way.

Polukranos, World Eater

{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.

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.

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 with X +1/+1 counters on it.

Khalni Hydra

This spell costs {G} less to cast for each green creature you control.
Trample

Hydra Broodmaster

{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.

Toxicrene

Reach, deathtouch
Hypertoxic Miasma — All lands have "{T}: Add one mana of any color" and lose all other abilities.

Growth Spiral

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

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.

Sprouting Phytohydra

Defender (This creature can't attack.)
Whenever Sprouting Phytohydra is dealt damage, you may create a token that's a copy of Sprouting Phytohydra.

Whiptongue Hydra

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

Vastwood Hydra

Vastwood Hydra enters 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.

Aspect of Hydra

Target creature gets +X/+X until end of turn, where X is your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

Polukranos, Unchained

Polukranos enters 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.

Overgrowth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}{G}.

Bioshift

Move any number of +1/+1 counters from target creature onto another target creature with the same controller.

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Savageborn Hydra

Double strike
Savageborn Hydra enters with X +1/+1 counters on it.
{1}{R/G}: Put a +1/+1 counter on Savageborn Hydra. Activate only as a sorcery.

Nessian Wilds Ravager

Tribute 6 (As this creature enters, an opponent of your choice may put six +1/+1 counters on it.)
When Nessian Wilds Ravager enters, if tribute wasn't paid, you may have Nessian Wilds Ravager fight another target creature. (Each deals damage equal to its power to the other.)

Hydra Omnivore

Whenever Hydra Omnivore deals combat damage to an opponent, it deals that much damage to each other opponent.

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.

Steelbane Hydra

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

Kodama of the West Tree

Reach
Modified creatures you control have trample. (Equipment, Auras you control, and counters are modifications.)
Whenever a modified creature you control deals combat damage to a player, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Domesticated Hydra

{X}{G}{G}{G}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
As long as Domesticated Hydra is monstrous, it has trample.

Lair of the Hydra

If you control two or more other lands, Lair of the Hydra enters 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.

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.

Phyrexian Hydra

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
If damage would be dealt to Phyrexian Hydra, prevent that damage. Put a -1/-1 counter on Phyrexian Hydra for each 1 damage prevented this way.

Nexos

Strategic Coordinator — Basic lands you control have "{T}: Add {C}{C}. Spend this mana only on costs that contain {X}."

Inspiring Call

Draw a card for each creature you control with a +1/+1 counter on it. Those creatures gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Servant of the Conduit

When Servant of the Conduit enters, you get {E}{E} (two energy counters).
{T}, Pay {E}: Add one mana of any color.

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 with X +1/+1 counters on it.

Roiling Regrowth

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

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.

Benevolent Hydra

Benevolent Hydra enters with X +1/+1 counters on it.
If one or more +1/+1 counters would be put on another creature you control, that many plus one +1/+1 counters are put on it instead.
{T}, Remove a +1/+1 counter from Benevolent Hydra: Put a +1/+1 counter on another target creature you control.

Mistcutter Hydra

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

Najeela, the Blade-Blossom

Whenever a Warrior attacks, you may have its controller create a 1/1 white Warrior creature token that's tapped and attacking.
{W}{U}{B}{R}{G}: Untap all attacking creatures. They gain trample, lifelink, and haste until end of turn. After this phase, there is an additional combat phase. Activate only during combat.

Apex Devastator

Cascade, cascade, cascade, cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order. Multiple instances of cascade each trigger separately.)

Herald of Secret Streams

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

Ulasht, the Hate Seed

Ulasht, the Hate Seed enters with a +1/+1 counter on it for each other red creature you control and a +1/+1 counter on it for each other green creature you control.
{1}, Remove a +1/+1 counter from Ulasht: Choose one —
• Ulasht deals 1 damage to target creature.
• Create a 1/1 green Saproling creature token.

Exponential Growth

Until end of turn, double target creature's power X times.

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

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.)

Apocalypse Hydra

Apocalypse Hydra enters with X +1/+1 counters on it. If X is 5 or more, it enters with an additional X +1/+1 counters on it.
{1}{R}, Remove a +1/+1 counter from Apocalypse Hydra: It deals 1 damage to any target.

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.)

Ironscale Hydra

If a creature would deal combat damage to Ironscale Hydra, prevent that damage and put a +1/+1 counter on Ironscale Hydra.

Briar Hydra

Trample
Domain — Whenever Briar Hydra deals combat damage to a player, put X +1/+1 counters on target creature you control, where X is the number of basic land types among lands you control.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Plasm Capture

Counter target spell. At the beginning of your next first main phase, add X mana in any combination of colors, where X is that spell's mana value.

Winged Hive Tyrant

Flying, haste
The Will of the Hive Mind — Other creatures you control with counters on them have flying and haste.

Primordial Hydra

Primordial Hydra enters 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.

Grakmaw, Skyclave Ravager

Grakmaw, Skyclave Ravager enters 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.

Thunderous Snapper

Whenever you cast a spell with mana value 5 or greater, draw a card.

Scourge of Skola Vale

Trample
Scourge of Skola Vale enters with two +1/+1 counters on it.
{T}, Sacrifice another creature: Put a number of +1/+1 counters on Scourge of Skola Vale equal to the sacrificed creature's toughness.

Oran-Rief, the Vastwood

Oran-Rief, the Vastwood enters tapped.
{T}: Add {G}.
{T}: Put a +1/+1 counter on each green creature that entered this turn.

Voracious Hydra

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

Rosheen Meanderer

{T}: Add {C}{C}{C}{C}. Spend this mana only on costs that contain {X}.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

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.