Stumpsquall Hydra

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

Command Tower

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

Strength of the Pack

Put two +1/+1 counters on each creature you control.

Plains

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.

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.

Biogenic Upgrade

Distribute three +1/+1 counters among one, two, or three target creatures, then double the number of +1/+1 counters on each of those creatures.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

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.

Druid's Deliverance

Prevent all combat damage that would be dealt to you this turn. Populate. (Create a token that's a copy of a creature token you control.)

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Grasslands

Grasslands enters tapped.
{T}, Sacrifice Grasslands: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Sol Ring

Stave Off

Target creature gains protection from the color of your choice until end of turn.

Commander's Sphere

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

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.)

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.

Fortified Village

As Fortified Village enters, you may reveal a Forest or Plains card from your hand. If you don't, Fortified Village enters tapped.
{T}: Add {G} or {W}.

Sundering Growth

Destroy target artifact or enchantment, then populate. (Create a token that's a copy of a creature token you control.)

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.

Canopy Vista

({T}: Add {G} or {W}.)
Canopy Vista enters tapped unless you control two or more basic lands.

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.)

Growing Ranks

At the beginning of your upkeep, populate. (Create a token that's a copy of a creature token you control.)

Restless Prairie

Restless Prairie enters tapped.
{T}: Add {G} or {W}.
{2}{G}{W}: Restless Prairie becomes a 3/3 green and white Llama creature until end of turn. It's still a land.
Whenever Restless Prairie attacks, other creatures you control get +1/+1 until end of turn.

Arcane Signet

Traverse the Outlands

Search your library for up to X basic land cards, where X is the greatest power among creatures you control. Put those cards onto the battlefield tapped, then shuffle.

Forest

Scattered Groves

({T}: Add {G} or {W}.)
Scattered Groves enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Karametra, God of Harvests

Indestructible
As long as your devotion to green and white is less than seven, Karametra isn't a creature.
Whenever you cast a creature spell, you may search your library for a Forest or Plains card, put it onto the battlefield tapped, then shuffle.

Temur Sabertooth

{1}{G}: You may return another creature you control to its owner's hand. If you do, Temur Sabertooth gains indestructible until end of turn.

Invigorating Surge

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

Trostani's Judgment

Exile target creature, then populate. (Create a token that's a copy of a creature token you control.)

Ground Seal

When Ground Seal enters, draw a card.
Cards in graveyards can't be the targets of spells or abilities.

Polukranos, Engine of Ruin

Reach, lifelink
Whenever Polukranos, Engine of Ruin or another nontoken Hydra you control dies, create a 3/3 green and white Phyrexian Hydra creature token with reach and a 3/3 green and white Phyrexian Hydra creature token with lifelink.

Polukranos Reborn

Reach
{6}{W/P}: Transform Polukranos Reborn. Activate only as a sorcery. ({W/P} can be paid with either {W} or 2 life.)

Polukranos Reborn // Polukranos, Engine of Ruin

Noxious Assault

Creatures you control get +2/+2 until end of turn. Whenever a creature blocks this turn, its controller gets a poison counter.

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}.)