Savageborn Hydra

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

Yavimaya Hollow

{T}: Add {C}.
{G}, {T}: Regenerate target creature.

Greenwarden of Murasa

When this creature enters, you may return target card from your graveyard to your hand.
When this creature dies, you may exile it. If you do, return target card from your graveyard to your hand.

Mountain

Khenra Charioteer

Trample
Other creatures you control have 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 this creature becomes monstrous, create X X/X green Hydra creature tokens.

Sakura-Tribe Elder

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

Horizon Stone

If you would lose unspent mana, that mana becomes colorless instead.

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.

Command Tower

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

Jiwari, the Earth Aflame

{X}{R}, {T}: Jiwari deals X damage to target creature without flying.
Channel — {X}{R}{R}{R}, Discard this card: It deals X damage to each creature without flying.

Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Timber Gorge

This land enters tapped.
{T}: Add {R} or {G}.

Beastcaller Savant

Haste
{T}: Add one mana of any color. Spend this mana only to cast a creature spell.

Mage Slayer

Whenever equipped creature attacks, it deals damage equal to its power to the player or planeswalker it's attacking.
Equip {3}

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.

Elvish Mystic

Vivid Crag

This land enters tapped with two charge counters on it.
{T}: Add {R}.
{T}, Remove a charge counter from this land: Add one mana of any color.

Forest

Cinder Glade

({T}: Add {R} or {G}.)
This land enters tapped unless you control two or more basic lands.

Vivid Grove

This land enters tapped with two charge counters on it.
{T}: Add {G}.
{T}, Remove a charge counter from this land: Add one mana of any color.

Harmonize

Seeker of Skybreak

Lightning Serpent

Trample, haste
This creature enters with X +1/+0 counters on it.
At the beginning of the end step, sacrifice this creature.

Magus of the Candelabra

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 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.

Wildcall

Manifest the top card of your library, then put X +1/+1 counters on it. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Kessig Wolf Run

{T}: Add {C}.
{X}{R}{G}, {T}: Target creature gets +X/+0 and gains trample until end of turn.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Rampant Growth

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

Ancient Grudge

Destroy target artifact.
Flashback {G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.)

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.

Fellwar Stone

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

Frontier Siege

As this enchantment enters, choose Khans or Dragons.
• Khans — At the beginning of each of your main phases, add {G}{G}.
• Dragons — Whenever a creature you control with flying enters, you may have it fight target creature you don't control.

Sylvan Caryatid

Defender, hexproof
{T}: Add one mana of any color.

Whisperer of the Wilds

{T}: Add {G}.
Ferocious — {T}: Add {G}{G}. Activate only if you control a creature with power 4 or greater.

Crater's Claws

Crater's Claws deals X damage to any target.
Ferocious — Crater's Claws deals X plus 2 damage instead if you control a creature with power 4 or greater.

Fungal Reaches

{T}: Add {C}.
{1}, {T}: Put a storage counter on this land.
{1}, Remove X storage counters from this land: Add X mana in any combination of {R} and/or {G}.

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.

Kodama's Reach

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.

Burst of Strength

Put a +1/+1 counter on target creature and untap it.

Crackle with Power

Crackle with Power deals five times X damage to each of up to X targets.

Clan Defiance

Choose one or more —
• Clan Defiance deals X damage to target creature with flying.
• Clan Defiance deals X damage to target creature without flying.
• Clan Defiance deals X damage to target player or planeswalker.

Fall of the Titans

Surge {X}{R} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Fall of the Titans deals X damage to each of up to two targets.

Aim High

Untap target creature. It gets +2/+2 and gains reach until end of turn.

Talisman of Impulse

{T}: Add {C}.
{T}: Add {R} or {G}. This artifact deals 1 damage to you.

Emerald Charm

Choose one —
• Untap target permanent.
• Destroy target non-Aura enchantment.
• Target creature loses flying until end of turn.

Hedron Archive

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

Sol Ring

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.

Klauth's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Breathe Flame — Klauth's Will deals X damage to each creature without flying.
• Smash Relics — Destroy up to X target artifacts and/or enchantments.

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.

Fanning the Flames

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Fanning the Flames deals X damage to any target.

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.

Llanowar Elves

Neverwinter Hydra

As this creature 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}.)

Outpost Siege

As this enchantment enters, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card.
• Dragons — Whenever a creature you control leaves the battlefield, this enchantment deals 1 damage to any target.

Wildest Dreams

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

Apocalypse Hydra

This creature 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 this creature: It deals 1 damage to any target.

Orochi Hatchery

This artifact enters with X charge counters on it.
{5}, {T}: Create a 1/1 green Snake creature token for each charge counter on this artifact.

Rosheen Meanderer

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

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.

Commune with Lava

Exile the top X cards of your library. Until the end of your next turn, you may play those cards.

Mistcutter Hydra

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

Electrodominance

Electrodominance deals X damage to any target. You may cast a spell with mana value X or less from your hand without paying its mana cost.

Rolling Thunder

Rolling Thunder deals X damage divided as you choose among any number of targets.

Gruul Signet

Verdeloth the Ancient

Kicker {X} (You may pay an additional {X} as you cast this spell.)
Saproling creatures and other Treefolk creatures get +1/+1.
When Verdeloth enters, if it was kicked, create X 1/1 green Saproling creature tokens.

Highland Weald

Disintegrate

Disintegrate deals X damage to any target. If it's a creature, it can't be regenerated this turn, and if it would die this turn, exile it instead.

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}.

Pinecrest Ridge

{T}: Add {C}.
{T}: Add {R} or {G}. This land doesn't untap during your next untap step.

Endless One

This creature enters with X +1/+1 counters on it.

Fyndhorn Elves

Shaman of Forgotten Ways

{T}: Add two mana in any combination of colors. Spend this mana only to cast creature spells.
Formidable — {9}{G}{G}, {T}: Each player's life total becomes the number of creatures they control. Activate only if creatures you control have total power 8 or greater.

Garruk's Uprising

When this enchantment enters, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)
Whenever a creature you control with power 4 or greater enters, draw a card.

Burn from Within

Burn from Within deals X damage to any target. If a creature is dealt damage this way, it loses indestructible until end of turn. If that creature would die this turn, exile it instead.

Cultivate

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.
This creature enters with X +1/+1 counters on it.