Thraben Inspector

When Thraben Inspector enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Nebelgast Herald

Flash (You may cast this spell any time you could cast an instant.)
Flying
Whenever Nebelgast Herald or another Spirit you control enters, tap target creature an opponent controls.

Humble the Brute

Destroy target creature with power 4 or greater.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Drogskol Shieldmate

Flash (You may cast this spell any time you could cast an instant.)
When Drogskol Shieldmate enters, other creatures you control get +0/+1 until end of turn.

Drunau Corpse Trawler

When Drunau Corpse Trawler enters, create a 2/2 black Zombie creature token.
{2}{B}: Target Zombie gains deathtouch until end of turn.

Niblis of Dusk

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Apothecary Geist

Flying
When Apothecary Geist enters, if you control another Spirit, you gain 3 life.

Emissary of the Sleepless

Flying
When Emissary of the Sleepless enters, if a creature died this turn, create a 1/1 white Spirit creature token with flying.

Unsubstantiate

Return target spell or creature to its owner's hand.

Perfected Form

Aberrant Researcher

Flying
At the beginning of your upkeep, mill a card. If an instant or sorcery card was milled this way, transform Aberrant Researcher.

Aberrant Researcher // Perfected Form

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.

Island

Topplegeist

Flying
When Topplegeist enters, tap target creature an opponent controls.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, tap target creature that player controls.

Long Road Home

Exile target creature. At the beginning of the next end step, return that card to the battlefield under its owner's control with a +1/+1 counter on it.

Erdwal Illuminator

Flying
Whenever you investigate for the first time each turn, investigate an additional time.

Displace

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.

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.