Plains

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.

Hallowed Spiritkeeper

Vigilance
When Hallowed Spiritkeeper dies, create X 1/1 white Spirit creature tokens with flying, where X is the number of creature cards in your graveyard.

Midnight Haunting

Create two 1/1 white Spirit creature tokens with flying.

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.

Solemn Offering

Destroy target artifact or enchantment. You gain 4 life.

Spectral Procession

Create three 1/1 white Spirit creature tokens with flying.

Geist-Honored Monk

Vigilance
Geist-Honored Monk's power and toughness are each equal to the number of creatures you control.
When Geist-Honored Monk enters, create two 1/1 white Spirit creature tokens with flying.

Requiem Angel

Flying
Whenever another non-Spirit creature you control dies, create a 1/1 white Spirit creature token with flying.

Spirit Bonds

Whenever a nontoken creature you control enters, you may pay {W}. If you do, create a 1/1 white Spirit creature token with flying.
{1}{W}, Sacrifice a Spirit: Target non-Spirit creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Arrest

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.

Field of Souls

Whenever a nontoken creature is put into your graveyard from the battlefield, create a 1/1 white Spirit creature token with flying.

Worthy Knight

Whenever you cast a Knight spell, create a 1/1 white Human creature token.

Intangible Virtue

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

Celestial Crusader

Flash
Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Flying
Other white creatures get +1/+1.

Skullclamp

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

Doomed Traveler

When Doomed Traveler dies, create a 1/1 white Spirit creature token with flying.

Beckon Apparition

Exile target card from a graveyard. Create a 1/1 white and black Spirit creature token with flying.