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.

Dauntless Survivor

When this creature enters, put a +1/+1 counter on target creature.

Island

Gift of the Viper

Put a +1/+1 counter, a reach counter, and a deathtouch counter on target creature. Untap it.

Applied Biomancy

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

Vigean Hydropon

Graft 5 (This creature enters with five +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
This creature can't attack or block.

Forest

Elven Rite

Distribute two +1/+1 counters among one or two target creatures.

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.)

Forced Adaptation

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.

Needlethorn Drake

Tangled Islet

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

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.)

Earthen Arms

Put two +1/+1 counters on target permanent.
Awaken 4—{6}{G} (If you cast this spell for {6}{G}, also put four +1/+1 counters on target land you control and it becomes a 0/0 Elemental creature with haste. It's still a land.)

Drakewing Krasis

Bioshift

Move any number of +1/+1 counters from target creature onto another target creature with the same controller.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Pollenbright Druid

When this creature enters, choose one —
• Put a +1/+1 counter on target creature.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Courage in Crisis

Put a +1/+1 counter on target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Rimewood Falls

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.)

Mutant's Prey

Target creature you control with a +1/+1 counter on it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)