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.

Militia's Pride

Whenever a nontoken creature you control attacks, you may pay {W}. If you do, create a 1/1 white Kithkin Soldier creature token that's tapped and attacking.

Brigid, Hero of Kinsbaile

First strike
{T}: Brigid, Hero of Kinsbaile deals 2 damage to each attacking or blocking creature target player controls.

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.)

Goldmeadow Stalwart

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

Ballyrush Banneret

Kithkin spells and Soldier spells you cast cost {1} less to cast.

Kithkin Rabble

Vigilance
Kithkin Rabble's power and toughness are each equal to the number of white permanents you control.

Plains

Kithkin Soldier

Cenn's Heir

Whenever Cenn's Heir attacks, it gets +1/+1 until end of turn for each other attacking Kithkin.

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.

Surge of Thoughtweft

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

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.