Have

Kinsbaile Aspirant

As an additional cost to cast this spell, behold a Kithkin or pay {2}. (To behold a Kithkin, choose a Kithkin you control or reveal a Kithkin card from your hand.)
Whenever another creature you control enters, this creature gets +1/+1 until end of turn.

Kinscaer Sentry

First strike, lifelink
Whenever this creature attacks, you may put a creature card with mana value X or less from your hand onto the battlefield tapped and attacking, where X is the number of attacking creatures you control.

Eclipsed Kithkin

When this creature enters, look at the top four cards of your library. You may reveal a Kithkin, Forest, or Plains card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Gallant Fowlknight

When this creature enters, creatures you control get +1/+0 until end of turn. Kithkin creatures you control also gain first strike until end of turn.

Surly Farrier

{T}: Target creature you control gets +1/+1 and gains vigilance until end of turn. Activate only as a sorcery.

Goldmeadow Nomad

{W}, Exile this card from your graveyard: Create a 1/1 green and white Kithkin creature token. Activate only as a sorcery.

Thoughtweft Lieutenant

Whenever this creature or another Kithkin you control enters, target creature you control gets +1/+1 and gains trample until end of turn.

Want

Springleaf Parade

When this enchantment enters, create X 1/1 colorless Shapeshifter creature tokens with changeling. (They're every creature type.)
Creature tokens you control have "{T}: Add one mana of any color."

Brigid, Doun's Mind

{T}: Add X {G} or X {W}, where X is the number of other creatures you control.
At the beginning of your first main phase, you may pay {W}. If you do, transform Brigid.

Brigid, Clachan's Heart

Whenever this creature enters or transforms into Brigid, Clachan's Heart, create a 1/1 green and white Kithkin creature token.
At the beginning of your first main phase, you may pay {G}. If you do, transform Brigid.

Brigid, Clachan's Heart // Brigid, Doun's Mind

Crossroads Watcher

Trample
Whenever another creature you control enters, this creature gets +1/+0 until end of turn.

Reluctant Dounguard

This creature enters with two -1/-1 counters on it.
Whenever another creature you control enters while this creature has a -1/-1 counter on it, remove a -1/-1 counter from this creature.

Wary Farmer

At the beginning of your end step, if another creature entered the battlefield under your control this turn, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Timid Shieldbearer

{4}{W}: Creatures you control get +1/+1 until end of turn.

Mistmeadow Council

This spell costs {1} less to cast if you control a Kithkin.
When this creature enters, draw a card.

Brigid's Command

Choose two —
• Create a token that's a copy of target Kithkin you control.
• Target player creates a 1/1 green and white Kithkin creature token.
• Target creature you control gets +3/+3 until end of turn.
• Target creature you control fights target creature an opponent controls.

Figure of Fable

{G/W}: This creature becomes a Kithkin Scout with base power and toughness 2/3.
{1}{G/W}{G/W}: If this creature is a Scout, it becomes a Kithkin Soldier with base power and toughness 4/5.
{3}{G/W}{G/W}{G/W}: If this creature is a Soldier, it becomes a Kithkin Avatar with base power and toughness 7/8 and protection from each of your opponents.

Thoughtweft Imbuer

Whenever a creature you control attacks alone, it gets +X/+X until end of turn, where X is the number of Kithkin you control.

Champion of the Clachan

Flash
As an additional cost to cast this spell, behold a Kithkin and exile it. (Exile a Kithkin you control or a Kithkin card from your hand.)
Other Kithkin you control get +1/+1.
When this creature leaves the battlefield, return the exiled card to its owner's hand.