Kiora, Behemoth Beckoner

Whenever a creature with power 4 or greater enters the battlefield under your control, draw a card.
−1: Untap target permanent.

Plains

Chromatic Orrery

You may spend mana as though it were mana of any color.
{T}: Add {C}{C}{C}{C}{C}.
{5}, {T}: Draw a card for each color among permanents you control.

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.

Solidarity of Heroes

Strive — This spell costs {1}{G} more to cast for each target beyond the first.
Choose any number of target creatures. Double the number of +1/+1 counters on each of them.

The Great Henge

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.

Primal Vigor

If one or more tokens would be created, twice that many of those tokens are created instead.
If one or more +1/+1 counters would be put on a creature, twice that many +1/+1 counters are put on that creature instead.

Overwhelming Stampede

Until end of turn, creatures you control gain trample and get +X/+X, where X is the greatest power among creatures 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 the battlefield, you may search your library for a land card, put it onto the battlefield tapped, then shuffle.

Kalonian Hydra

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

Steelbane Hydra

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.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

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.

Path of Ancestry

Path of Ancestry enters the battlefield tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Forest

Taiga

Primordial Hydra

Primordial Hydra enters the battlefield 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.

Thran Dynamo

Mirari's Wake

Creatures you control get +1/+1.
Whenever you tap a land for mana, add one mana of any type that land produced.

Swamp

Mountain

Zendikar Resurgent

Whenever you tap a land for mana, add one mana of any type that land produced. (The types of mana are white, blue, black, red, green, and colorless.)
Whenever you cast a creature spell, draw a card.

Overgrown Tomb

({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.

Mistcutter Hydra

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

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.

Castle Garenbrig

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.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Explosive Vegetation

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

Whiptongue Hydra

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

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Skyshroud Claim

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

Oran-Rief Hydra

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.

Command Tower

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

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.

Temple Garden

({T}: Add {G} or {W}.)
As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Vastwood Hydra

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.

Lifeblood Hydra

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.

Nyxbloom Ancient

Trample
If you tap a permanent for mana, it produces three times as much of that mana instead.

Feral Hydra

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.

Managorger Hydra

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

Temple of the False God

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

Stomping Ground

({T}: Add {R} or {G}.)
As Stomping Ground enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Hydra Omnivore

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

Rhythm of the Wild

Creature spells you control can't be countered.
Nontoken creatures you control have riot. (They enter the battlefield with your choice of a +1/+1 counter or haste.)

Apocalypse Hydra

Apocalypse Hydra enters the battlefield with X +1/+1 counters on it. If X is 5 or more, it enters the battlefield 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.

Kodama's Reach

Savageborn Hydra

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

Karn's Bastion

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

Heroes' Bane

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

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.

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.

Island

Unbound Flourishing

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.

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 the battlefield with X +1/+1 counters on it.

Rampant Growth

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

Gyrus, Waker of Corpses

Gyrus, Waker of Corpses enters the battlefield 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.

Akroma's Memorial

Creatures you control have flying, first strike, vigilance, trample, haste, and protection from black and from red.

Khalni Hydra

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

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.

Asceticism

Creatures you control have hexproof.
{1}{G}: Regenerate target creature. (The next time it would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Ironscale Hydra

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

Boundless Realms

Search your library for up to X basic land cards, where X is the number of lands you control, put them onto the battlefield tapped, then shuffle.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Rugged Highlands

Rugged Highlands enters the battlefield tapped.
When Rugged Highlands enters the battlefield, you gain 1 life.
{T}: Add {R} or {G}.

Phytohydra

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

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Mana Reflection

If you tap a permanent for mana, it produces twice as much of that mana instead.

Jungle Hollow

Jungle Hollow enters the battlefield tapped.
When Jungle Hollow enters the battlefield, you gain 1 life.
{T}: Add {B} or {G}.

Farseek

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

Sol Ring

Progenitus

Protection from everything
If Progenitus would be put into a graveyard from anywhere, reveal Progenitus and shuffle it into its owner's library instead.

Breeding Pool

({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.

Unclaimed Territory

As Unclaimed Territory enters the battlefield, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Grakmaw, Skyclave Ravager

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.

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 the battlefield with X +1/+1 counters on it.

Protean Hydra

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.

Herald's Horn

As Herald's Horn enters the battlefield, 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.

Mortify

Urza's Incubator

As Urza's Incubator enters the battlefield, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Hungering Hydra

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.)

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.

Voracious Hydra

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.

Heroic Intervention

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

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.)

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.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters the battlefield, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.