Thoughtweft Trio

First strike, vigilance
Champion a Kithkin (When this enters, sacrifice it unless you exile another Kithkin you control. When this leaves the battlefield, that card returns to the battlefield.)
Thoughtweft Trio can block any number of creatures.

Windbrisk Heights

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
Windbrisk Heights enters tapped.
{T}: Add {W}.
{W}, {T}: You may play the exiled card without paying its mana cost if you attacked with three or more creatures this turn.

Crib Swap

Changeling (This card is every creature type.)
Exile target creature. Its controller creates a 1/1 colorless Shapeshifter creature token with changeling.

Goldmeadow Stalwart

As an additional cost to cast this spell, reveal a Kithkin card from your hand or pay {3}.

Swords to Plowshares

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

Knight of Meadowgrain

First strike
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Kithkin Harbinger

When Kithkin Harbinger enters, you may search your library for a Kithkin card, reveal it, then shuffle and put that card on top.

Plains

Surge of Thoughtweft

Creatures you control get +1/+1 until end of turn. If you control a Kithkin, draw a card.

Amrou Kithkin

Amrou Kithkin can't be blocked by creatures with power 3 or greater.

Rally the Ranks

As Rally the Ranks enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.

Kinsbaile Borderguard

Kinsbaile Borderguard enters with a +1/+1 counter on it for each other Kithkin you control.
When Kinsbaile Borderguard dies, create a 1/1 white Kithkin Soldier creature token for each counter on it.

Figure of Destiny

{R/W}: Figure of Destiny becomes a Kithkin Spirit with base power and toughness 2/2.
{R/W}{R/W}{R/W}: If Figure of Destiny is a Spirit, it becomes a Kithkin Spirit Warrior with base power and toughness 4/4.
{R/W}{R/W}{R/W}{R/W}{R/W}{R/W}: If Figure of Destiny is a Warrior, it becomes a Kithkin Spirit Warrior Avatar with base power and toughness 8/8, flying, and first strike.

Rustic Clachan

As Rustic Clachan enters, you may reveal a Kithkin card from your hand. If you don't, Rustic Clachan enters tapped.
{T}: Add {W}.
Reinforce 1—{1}{W} ({1}{W}, Discard this card: Put a +1/+1 counter on target creature.)

Ajani's Presence

Strive — This spell costs {2}{W} more to cast for each target beyond the first.
Any number of target creatures each get +1/+1 and gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Galepowder Mage

Flying
Whenever Galepowder Mage attacks, exile another target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.