Scapegoat

As an additional cost to cast this spell, sacrifice a creature.
Return any number of target creatures you control to their owner's hand.

Clarion Spirit

Whenever you cast your second spell each turn, create a 1/1 white Spirit creature token with flying.

Thalisse, Reverent Medium

At the beginning of each end step, create X 1/1 white Spirit creature tokens with flying, where X is the number of tokens you created this turn.

King of the Oathbreakers

Flying
Whenever King of the Oathbreakers or another Spirit you control becomes the target of a spell, it phases out. (Treat it and anything attached to it as though they don't exist until your next turn.)
Whenever King of the Oathbreakers or another Spirit you control phases in, create a tapped 1/1 white Spirit creature token with flying.

Swords to Plowshares

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

Oyobi, Who Split the Heavens

Flying
Whenever you cast a Spirit or Arcane spell, create a 3/3 white Spirit creature token with flying.

Cauldron Haze

Choose any number of target creatures. Each of those creatures gains persist until end of turn. (When it 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.)

Windborn Muse

Flying
Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Twilight Drover

Whenever a creature token leaves the battlefield, put a +1/+1 counter on Twilight Drover.
{2}{W}, Remove a +1/+1 counter from Twilight Drover: Create two 1/1 white Spirit creature tokens with flying.

Selfless Spirit

Flying
Sacrifice Selfless Spirit: Creatures you control gain indestructible until end of turn.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Drogskol Reinforcements

Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Other Spirits you control have melee.
Prevent all noncombat damage that would be dealt to Spirits you control.

Intangible Virtue

Creature tokens you control get +1/+1 and have vigilance.

Myojin of Blooming Dawn

Myojin of Blooming Dawn enters with an indestructible counter on it if you cast it from your hand.
Remove an indestructible counter from Myojin of Blooming Dawn: Create a 1/1 colorless Spirit creature token for each permanent you control.