Assimilate Essence

Counter target creature or battle spell unless its controller pays {4}. If they do, you incubate 2. (Create an Incubator token with two +1/+1 counters on it and "{2}: Transform this token." It transforms into a 0/0 Phyrexian artifact creature.)

Simic Sky Swallower

Flying, trample
Shroud (This creature can't be the target of spells or abilities.)

Simic Keyrune

{T}: Add {G} or {U}.
{G}{U}: This artifact becomes a 2/3 green and blue Crab artifact creature with hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Gruul Charm

Choose one —
• Creatures without flying can't block this turn.
• Gain control of all permanents you own.
• Gruul Charm deals 3 damage to each creature with flying.

Applied Biomancy

Choose one or both —
• Target creature gets +1/+1 until end of turn.
• Return target creature to its owner's hand.

Bladecoil Serpent

When this creature enters, for each {U}{U} spent to cast it, draw a card.
When this creature enters, for each {B}{B} spent to cast it, each opponent discards a card.
When this creature enters, for each {R}{R} spent to cast it, it gets +1/+0 and gains trample and haste until end of turn.

Command Tower

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

Aim High

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

Simic Cluestone

{T}: Add {G} or {U}.
{G}{U}, {T}, Sacrifice this artifact: Draw a card.

Xyris, the Writhing Storm

Flying
Whenever an opponent draws a card except the first one they draw in each of their draw steps, create a 1/1 green Snake creature token.
Whenever Xyris deals combat damage to a player, you and that player each draw that many cards.

Feiyi Snake

Reach (This creature can block creatures with flying.)

Ancient Grudge

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

Gruul Guildgate

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

Boon of Boseiju

Target creature gets +X/+X until end of turn, where X is the greatest mana value among permanents you control. Untap it.

Aetherize

Return all attacking creatures to their owner's hand.

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.)

Gruul Locket

{T}: Add {R} or {G}.
{R/G}{R/G}{R/G}{R/G}, {T}, Sacrifice this artifact: Draw two cards.

Stonecoil Serpent

Reach, trample, protection from multicolored
This creature enters with X +1/+1 counters on it.

Simic Guildgate

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

Gruul Keyrune

{T}: Add {R} or {G}.
{R}{G}: This artifact becomes a 3/2 red and green Beast artifact creature with trample until end of turn.

Accelerated Mutation

Target creature gets +X/+X until end of turn, where X is the greatest mana value among permanents you control.

Anticipate

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Blessed Respite

Target player shuffles their graveyard into their library. Prevent all combat damage that would be dealt this turn.

Ancient Animus

Put a +1/+1 counter on target creature you control if it's legendary. Then it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Band Together

Up to two target creatures you control each deal damage equal to their power to another target creature.

Serpentine Ambush

Until end of turn, target creature becomes a blue Serpent with base power and toughness 5/5.

Cryptic Serpent

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.

Blustersquall

Tap target creature you don't control.
Overload {3}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Simic Charm

Choose one —
• Target creature gets +3/+3 until end of turn.
• Permanents you control gain hexproof until end of turn.
• Return target creature to its owner's hand.

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.)

Annul

Counter target artifact or enchantment spell.

Barge In

Target attacking creature gets +2/+2 until end of turn. Each attacking non-Human creature gains trample 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.)

Bestow Greatness

Target creature gets +4/+4 and gains trample until end of turn.

Alchemist's Retrieval

Cleave {1}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Return target nonland permanent [you control] to its owner's hand.

Antagonize

Target creature gets +4/+3 until end of turn.

Blitz of the Thunder-Raptor

Blitz of the Thunder-Raptor deals damage to target creature or planeswalker equal to the number of instant and sorcery cards in your graveyard. If that creature or planeswalker would die this turn, exile it instead.

Ribbon Snake

Flying
{2}: This creature loses flying until end of turn. Any player may activate this ability.

Skyserpent Seeker

Flying, deathtouch
Exhaust — {4}: Reveal cards from the top of your library until you reveal two land cards. Put those land cards onto the battlefield tapped and the rest on the bottom of your library in a random order. Put a +1/+1 counter on this creature. (Activate each exhaust ability only once.)