Hallowed Fountain

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

Flooded Strand

{T}, Pay 1 life, Sacrifice this land: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Seachrome Coast

This land enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.

Rattlechains

Flash
Flying
When this creature enters, target Spirit gains hexproof until end of turn.
You may cast Spirit spells as though they had flash.

Supreme Phantom

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

Fabled Passage

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Teferi, Time Raveler

Each opponent can cast spells only any time they could cast a sorcery.
+1: Until your next turn, you may cast sorcery spells as though they had flash.
−3: Return up to one target artifact, creature, or enchantment to its owner's hand. Draw a card.

Moorland Haunt

{T}: Add {C}.
{W}{U}, {T}, Exile a creature card from your graveyard: Create a 1/1 white Spirit creature token with flying.

Selfless Spirit

Flying
Sacrifice this creature: Creatures you control gain indestructible until end of turn.

Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Skyclave Apparition

When this creature enters, exile up to one target nonland, nontoken permanent you don't control with mana value 4 or less.
When this creature leaves the battlefield, the exiled card's owner creates an X/X blue Illusion creature token, where X is the mana value of the exiled card.

Plains

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.

Negate

Mutavault

{T}: Add {C}.
{1}: This land becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Island

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

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.

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.)

Shacklegeist

Flying
This creature can block only creatures with flying.
Tap two untapped Spirits you control: Tap target creature you don't control.