Mausoleum Wanderer

Flying
Whenever another Spirit you control enters, this creature gets +1/+1 until end of turn.
Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {X}, where X is this creature's power.

Glasspool Shore

Glasspool Mimic

You may have this creature enter as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.

Glasspool Mimic // Glasspool Shore

Spell Queller

Flash
Flying
When this creature enters, exile target spell with mana value 4 or less.
When this creature leaves the battlefield, the exiled card's owner may cast that card without paying its mana cost.

Plains

Declaration in Stone

Exile target creature and all other creatures its controller controls with the same name as that creature. That player investigates for each nontoken creature exiled this way.

Mistgate Pathway

Hengegate Pathway

Hengegate Pathway // Mistgate Pathway

Hallowed Fountain

({T}: Add {W} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Supreme Phantom

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

Lofty Denial

Counter target spell unless its controller pays {1}. If you control a creature with flying, counter that spell unless its controller pays {4} instead.

Spectral Sailor

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

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Watery Grave

({T}: Add {U} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Island

Godless Shrine

({T}: Add {W} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Lingering Souls

Create two 1/1 white Spirit creature tokens with flying.
Flashback {1}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.)