Trusted Forcemage

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Trusted Forcemage is paired with another creature, each of those creatures gets +1/+1.

Wolfir Silverheart

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Wolfir Silverheart is paired with another creature, each of those creatures gets +4/+4.

Geist Trappers

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Geist Trappers is paired with another creature, both creatures have reach.

Nephalia Smuggler

{3}{U}, {T}: Exile another target creature you control, then return that card to the battlefield under your control.

Elgaud Shieldmate

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Elgaud Shieldmate is paired with another creature, both creatures have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Pathbreaker Wurm

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Pathbreaker Wurm is paired with another creature, both creatures have trample.

Wingcrafter

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Wingcrafter is paired with another creature, both creatures have flying.

Forest

Wolfir Avenger

Flash (You may cast this spell any time you could cast an instant.)
{1}{G}: Regenerate Wolfir Avenger.

Ice Cage

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.
When enchanted creature becomes the target of a spell or ability, destroy Ice Cage.

Llanowar Elves

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Acidic Slime enters, destroy target artifact, enchantment, or land.

Tandem Lookout

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Tandem Lookout is paired with another creature, each of those creatures has "Whenever this creature deals damage to an opponent, draw a card."

Deadeye Navigator

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Deadeye Navigator is paired with another creature, each of those creatures has "{1}{U}: Exile this creature, then return it to the battlefield under your control."

Joint Assault

Target creature gets +2/+2 until end of turn. If it's paired with a creature, that creature also gets +2/+2 until end of turn.

Latch Seeker

Nightshade Peddler

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Nightshade Peddler is paired with another creature, both creatures have deathtouch.

Overrun

Creatures you control get +3/+3 and gain trample until end of turn. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)

Lair Delve

Reveal the top two cards of your library. Put all creature and land cards revealed this way into your hand and the rest on the bottom of your library in any order.

Vorstclaw

Island

Druid's Familiar

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Druid's Familiar is paired with another creature, each of those creatures gets +2/+2.

Flowering Lumberknot

Flowering Lumberknot can't attack or block unless it's paired with a creature with soulbond.