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.)

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.

Stumpsquall Hydra

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

Return to Nature

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

Audacity

Enchant creature
Enchanted creature gets +2/+0 and has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)
When this Aura is put into a graveyard from the battlefield, draw a card.

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.

Hunter's Insight

Choose target creature you control. Whenever that creature deals combat damage to a player or planeswalker this turn, draw that many cards.

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.

Visions of Dominance

Put a +1/+1 counter on target creature, then double the number of +1/+1 counters on it.
Flashback {8}{G}{G}. This spell costs {X} less to cast this way, where X is the greatest mana value of a commander you own on the battlefield or in the command zone. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tyvar's Stand

Target creature you control gets +X/+X and gains hexproof and indestructible until end of turn. (A creature with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Ram Through

Target creature you control deals damage equal to its power to target creature you don't control. If the creature you control has trample, excess damage is dealt to that creature's controller instead.

Karametra's Acolyte

{T}: Add an amount of {G} equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

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.

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.

Wren's Run Hydra

Reach
This creature 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.)

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.

Capricopian

This creature enters with X +1/+1 counters on it.
{2}: Put a +1/+1 counter on this creature, then you may reselect which player this creature is attacking. Only the player this creature is attacking may activate this ability and only during the declare attackers step. (It can't attack its controller.)

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.

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.

Rampant Growth

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

Gaea's Gift

Put a +1/+1 counter on target creature you control. It gains reach, trample, hexproof, and indestructible until end of turn. (It can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Colossal Majesty

At the beginning of your upkeep, if you control a creature with power 4 or greater, draw a card.

Crowned Ceratok

Trample
Each creature you control with a +1/+1 counter on it has trample.

Explore

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

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.)

Snake Umbra

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals damage to an opponent, you may draw a card."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Season of Growth

Whenever a creature you control enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Whenever you cast a spell that targets a creature you control, draw a card.

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.

Return of the Wildspeaker

Choose one —
• Draw cards equal to the greatest power among non-Human creatures you control.
• Non-Human creatures you control get +3/+3 until end of turn.

Ranger's Guile

Target creature you control gets +1/+1 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Gwenna, Eyes of Gaea

{T}: Add two mana in any combination of colors. Spend this mana only to cast creature spells or activate abilities of creature sources.
Whenever you cast a creature spell with power 5 or greater, put a +1/+1 counter on Gwenna and untap it.

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.

Sol Ring

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.

Llanowar Tribe

Tiger Claws

Flash
Enchant creature
Enchanted creature gets +1/+1 and has trample.

Ironscale Hydra

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

Invigorating Surge

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

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.

Mortal's Resolve

Target creature gets +1/+1 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Belt of Giant Strength

Equipped creature has base power and toughness 10/10.
Equip {10}. This ability costs {X} less to activate, where X is the power of the creature it targets.

Hunter's Prowess

Until end of turn, target creature gets +3/+3 and gains trample and "Whenever this creature deals combat damage to a player, draw that many cards."

Wild Defiance

Whenever a creature you control becomes the target of an instant or sorcery spell, that creature gets +3/+3 until end of turn.

Withstand Death

Target creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it's still put into its owner's graveyard.)

Briar Hydra

Trample
Domain — Whenever this creature 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.

Hydra's Growth

Enchant creature
When this Aura enters, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.

Forest

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.)

Hydra Omnivore

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

Mistcutter Hydra

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

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}.)

Nexos

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

Summer Bloom

You may play up to three additional lands this turn.

Tamiyo's Safekeeping

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life. (A permanent with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

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.

Arcane Signet

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

Blossoming Defense

Target creature you control gets +2/+2 and gains hexproof until end of turn.

Sixth Sense

Enchant creature
Enchanted creature has "Whenever this creature deals combat damage to a player, you may draw a card."

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.

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.

Managorger Hydra

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

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.

Elvish Mystic

Wild Growth

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

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)