New Horizons

Enchant land
When this Aura enters, put a +1/+1 counter on target creature you control.
Enchanted land has "{T}: Add two mana of any one color."

Nessian Wilds Ravager

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

Castle Garenbrig

This land enters 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.

Mosswort Bridge

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
This land enters tapped.
{T}: Add {G}.
{G}, {T}: You may play the exiled card without paying its mana cost if creatures you control have total power 10 or greater.

Stumpsquall Hydra

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

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Explosive Vegetation

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

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.

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on this creature.

Cultivate

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.

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 this creature becomes monstrous, create X X/X green Hydra creature tokens.

Unravel the Aether

Choose target artifact or enchantment. Its owner shuffles it into their library.

Sol Ring

Vastwood Hydra

This creature enters with X +1/+1 counters on it.
When this creature dies, you may distribute a number of +1/+1 counters equal to the number of +1/+1 counters on this creature among any number of creatures you control.

Feral Hydra

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

The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Worn Powerstone

This artifact enters tapped.
{T}: Add {C}{C}.

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 fights up to one target creature you don't control.

Return to Nature

Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Exile target card from a graveyard.

Scourge of Skola Vale

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

Primordial Hydra

This creature enters with X +1/+1 counters on it.
At the beginning of your upkeep, double the number of +1/+1 counters on this creature.
This creature has trample as long as it has ten or more +1/+1 counters on it.

Krosan Grip

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.

Ulvenwald Hydra

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

Hooded Hydra

This creature enters with X +1/+1 counters on it.
When this creature dies, create a 1/1 green Snake creature token for each +1/+1 counter on it.
Morph {3}{G}{G}
As this creature is turned face up, put five +1/+1 counters on it.

Back to Nature

Doubling Season

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.

Vigor

Trample
If damage would be dealt to another creature you control, prevent that damage. Put a +1/+1 counter on that creature for each 1 damage prevented this way.
When Vigor is put into a graveyard from anywhere, shuffle it into its owner's library.

Wilt

Destroy target artifact or enchantment.
Cycling {2} ({2}, Discard this card: Draw a card.)

Explore

You may play an additional land this turn.
Draw a card.

Triumph of the Hordes

Until end of turn, creatures you control get +1/+1 and gain trample and infect. (Creatures with infect deal damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Mistcutter Hydra

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

Creeping Corrosion

Myriad Landscape

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

Khalni Hydra

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

Hydra Omnivore

Whenever this creature deals combat damage to an opponent, it deals that much damage to each other opponent.

Herald's Horn

As this artifact enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Steelbane Hydra

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

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.)

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Kodama's Reach

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.

Voracious Hydra

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

Overgrowth

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

Protean Hydra

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

Rancor

Enchant creature
Enchanted creature gets +2/+0 and has trample.
When this Aura is put into a graveyard from the battlefield, return it to its owner's hand.

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.)

Hungering Hydra

This creature enters with X +1/+1 counters on it.
This creature can't be blocked by more than one creature.
Whenever this creature is dealt damage, put that many +1/+1 counters on it. (It must survive the damage to get the counters.)

Elementalist's Palette

Whenever you cast a spell with {X} in its mana cost, put two charge counters on this artifact.
{T}: Add one mana of any color.
{T}: Add {C} for each charge counter on this artifact. Spend this mana only on costs that contain {X}.

Skyshroud Claim

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

Exploration

You may play an additional land on each of your turns.

Nissa's Pilgrimage

Search your library for up to two basic Forest cards, reveal those cards, and put one onto the battlefield tapped and the rest into your hand. Then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, search your library for up to three basic Forest cards instead of two.

Forest

Icon of Ancestry

As this artifact enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{3}, {T}: Look at the top three cards of your library. You may reveal a creature card of the chosen type from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Lair of the Hydra

If you control two or more other lands, this land enters tapped.
{T}: Add {G}.
{X}{G}: Until end of turn, this land becomes an X/X green Hydra creature. It's still a land. X can't be 0.

Oran-Rief Hydra

Trample
Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature. If that land is a Forest, put two +1/+1 counters on this creature instead.

Terastodon

When this creature enters, you may destroy up to three target noncreature permanents. For each permanent put into a graveyard this way, its controller creates a 3/3 green Elephant creature token.

Cultivator Colossus

Trample
Cultivator Colossus's power and toughness are each equal to the number of lands you control.
When this creature enters, you may put a land card from your hand onto the battlefield tapped. If you do, draw a card and repeat this process.

Vorinclex, Monstrous Raider

Trample, haste
If you would put one or more counters on a permanent or player, put twice that many of each of those kinds of counters on that permanent or player instead.
If an opponent would put one or more counters on a permanent or player, they put half that many of each of those kinds of counters on that permanent or player instead, rounded down.

Sisay's Ring

Sol Talisman

Suspend 3—{1} (Rather than cast this card from your hand, pay {1} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
{T}: Add {C}{C}.