Plains

Geistlight Snare

This spell costs {1} less to cast if you control a Spirit. It also costs {1} less to cast if you control an enchantment.
Counter target spell unless its controller pays {3}.

Patrician Geist

Flying
Other Spirits you control get +1/+1.
Spells you cast from your graveyard cost {1} less to cast.

Ancestor's Embrace

Enchant creature
Enchanted creature has lifelink.
If Ancestor's Embrace would be put into a graveyard from anywhere, exile it instead.

Kindly Ancestor

Lifelink
Disturb {1}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Kindly Ancestor // Ancestor's Embrace

Drogskol Captain

Flying
Other Spirit creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Aerial Assault

Destroy target tapped creature. You gain 1 life for each creature you control with flying.

Island

Azorius Chancery

Azorius Chancery enters tapped.
When Azorius Chancery enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Not Forgotten

Put target card from a graveyard on your choice of the top or bottom of its owner's library. Create a 1/1 white Spirit creature token with flying.

Valor of the Worthy

Enchant creature
Enchanted creature gets +1/+1.
When enchanted creature leaves the battlefield, create a 1/1 white Spirit creature token with flying.

Spectral Sailor

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.

Essence Flux

Exile target creature you control, then return that card to the battlefield under its owner's control. If it's a Spirit, put a +1/+1 counter on it.

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.

Twinblade Invocation

Enchant creature
Enchanted creature has double strike.
If Twinblade Invocation would be put into a graveyard from anywhere, exile it instead.

Twinblade Geist

Double strike
Disturb {2}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Twinblade Geist // Twinblade Invocation

Millicent, Restless Revenant

This spell costs {1} less to cast for each Spirit you control.
Flying
Whenever Millicent, Restless Revenant or another nontoken Spirit you control dies or deals combat damage to a player, create a 1/1 white Spirit creature token with flying.

Supreme Phantom

Flying
Other Spirits you control get +1/+1.

Dorothea's Retribution

Enchant creature
Enchanted creature has "Whenever this creature attacks, create a 4/4 white Spirit creature token with flying that's tapped and attacking. Sacrifice that token at end of combat."
If Dorothea's Retribution would be put into a graveyard from anywhere, exile it instead.

Dorothea, Vengeful Victim

Flying
When Dorothea, Vengeful Victim attacks or blocks, sacrifice it at end of combat.
Disturb {1}{W}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Dorothea, Vengeful Victim // Dorothea's Retribution

Tranquil Cove

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {W} or {U}.

Gutter Shortcut

Enchant creature
Enchanted creature can't be blocked as long as it's attacking alone.
If Gutter Shortcut would be put into a graveyard from anywhere, exile it instead.

Gutter Skulker

Gutter Skulker can't be blocked as long as it's attacking alone.
Disturb {3}{U} (You may cast this card from your graveyard transformed for its disturb cost.)