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.

Cenn's Heir

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

Kithkin Zephyrnaut

Kinship — At the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with Kithkin Zephyrnaut, you may reveal it. If you do, Kithkin Zephyrnaut gets +2/+2 and gains flying and vigilance until end of turn.

Kithkin Spellduster

Flying
{1}{W}, Sacrifice Kithkin Spellduster: Destroy target enchantment.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Somnomancer

When Somnomancer enters, you may tap target creature.

Ethereal Guidance

Creatures you control get +2/+1 until end of turn.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Bond of Discipline

Tap all creatures your opponents control. Creatures you control gain lifelink until end of turn.

Thistledown Liege

Flash
Other white creatures you control get +1/+1.
Other blue creatures you control get +1/+1.

Ballynock Cohort

First strike
Ballynock Cohort gets +1/+1 as long as you control another white creature.

Island

Plains

Knight of Meadowgrain

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

Wizened Cenn

Other Kithkin creatures you control get +1/+1.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Deliberate

Amass the Components

Draw three cards, then put a card from your hand on the bottom of your library.

Great Teacher's Decree

Creatures you control get +2/+1 until end of turn.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Amrou Seekers

Amrou Seekers can't be blocked except by artifact creatures and/or white creatures.

Drawn from Dreams

Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in a random order.

Faithful Mending

You gain 2 life, draw two cards, then discard two cards.
Flashback {1}{W}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Kithkin Rabble

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

Ballyrush Banneret

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

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.

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.