Wildslayer Elves

Wither (This deals damage to creatures in the form of -1/-1 counters.)

Fable of Wolf and Owl

Whenever you cast a green spell, you may create a 2/2 green Wolf creature token.
Whenever you cast a blue spell, you may create a 1/1 blue Bird creature token with flying.

Snakeform

Until end of turn, target creature loses all abilities and becomes a green Snake with base power and toughness 1/1.
Draw a card.

Evolving Wilds

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

Biomantic Mastery

Draw a card for each creature target player controls, then draw a card for each creature another target player controls.

Selkie Hedge-Mage

When Selkie Hedge-Mage enters, if you control two or more Forests, you may gain 3 life.
When Selkie Hedge-Mage enters, if you control two or more Islands, you may return target tapped creature to its owner's hand.

Simic Guildgate

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

Thrive

Put a +1/+1 counter on each of X target creatures.

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Infiltrator's Magemark

Enchant creature
Creatures you control that are enchanted get +1/+1 and can't be blocked except by creatures with defender.

Lorescale Coatl

Whenever you draw a card, put a +1/+1 counter on Lorescale Coatl.

Wistful Selkie

Evolution Vat

{3}, {T}: Tap target creature and put a +1/+1 counter on it. Until end of turn, that creature gains "{2}{G}{U}: Double the number of +1/+1 counters on this creature."

Gilder Bairn

{2}{G/U}, {Q}: Double the number of each kind of counter on target permanent. ({Q} is the untap symbol.)

Favor of the Overbeing

Enchant creature
As long as enchanted creature is green, it gets +1/+1 and has vigilance.
As long as enchanted creature is blue, it gets +1/+1 and has flying.

Writ of Passage

Enchant creature
Whenever enchanted creature attacks, if its power is 2 or less, it can't be blocked this turn.
Forecast — {1}{U}, Reveal Writ of Passage from your hand: Target creature with power 2 or less can't be blocked this turn. (Activate only during your upkeep and only once each turn.)

Winged Coatl

Flash (You may cast this spell any time you could cast an instant.)
Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Negate

Slippery Bogle

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Shorecrasher Mimic

Whenever you cast a spell that's both green and blue, Shorecrasher Mimic has base power and toughness 5/3 until end of turn and gains trample until end of turn.

Forest

Vedalken Heretic

Whenever Vedalken Heretic deals damage to an opponent, you may draw a card.

Train of Thought

Replicate {1}{U} (When you cast this spell, copy it for each time you paid its replicate cost.)
Draw a card.

Nulltread Gargantuan

When Nulltread Gargantuan enters, put a creature you control on top of its owner's library.

Invert the Skies

Creatures your opponents control lose flying until end of turn if {G} was spent to cast this spell, and creatures you control gain flying until end of turn if {U} was spent to cast this spell. (Do both if {G}{U} was spent.)

Island

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.