Unblinking Observer

{T}: Add {U}. Spend this mana only to pay a disturb cost or cast an instant or sorcery spell.

Neonate's Rush

This spell costs {1} less to cast if you control a Vampire.
Neonate's Rush deals 1 damage to target creature and 1 damage to its controller. Draw a card.

Vadrik, Astral Archmage

If it's neither day nor night, it becomes day as Vadrik, Astral Archmage enters.
Instant and sorcery spells you cast cost {X} less to cast, where X is Vadrik's power.
Whenever day becomes night or night becomes day, put a +1/+1 counter on Vadrik.

Storm Skreelix

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, Storm Skreelix gets +2/+0 until end of turn.

Otherworldly Gaze

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Embodiment of Flame

Whenever a spell you control deals damage, put a flame counter on Embodiment of Flame.
{1}, Remove a flame counter from Embodiment of Flame: Exile the top card of your library. You may play that card this turn.

Flame Channeler

When a spell you control deals damage, transform Flame Channeler.

Flame Channeler // Embodiment of Flame

Geistwave

Return target nonland permanent to its owner's hand. If you controlled that permanent, draw a card.

Island

Harvesttide Assailant

Trample
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Harvesttide Infiltrator

Trample
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Harvesttide Infiltrator // Harvesttide Assailant

Drownyard Amalgam

When Drownyard Amalgam enters, target player mills three cards. (They put the top three cards of their library into their graveyard.)
{2}{U}: Drownyard Amalgam can't be blocked this turn.

Mountain

Falcon Abomination

Flying
When Falcon Abomination enters, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Burn the Accursed

Burn the Accursed deals 5 damage to target creature and 2 damage to that creature's controller. If that creature would die this turn, exile it instead.

Shipwreck Sifters

When Shipwreck Sifters enters, draw a card, then discard a card.
Whenever you discard a Spirit card or a card with disturb, put a +1/+1 counter on Shipwreck Sifters.

Curse of Shaken Faith

Enchant player
Whenever enchanted player casts a spell other than the first spell they cast each turn or copies a spell, Curse of Shaken Faith deals 2 damage to them.

Startle

Target creature gets -2/-0 until end of turn. Create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
Draw a card.

Larder Zombie

Defender
Tap three untapped creatures you control: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Devious Cover-Up

Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard. You may shuffle up to four target cards from your graveyard into your library.

Firmament Sage

If it's neither day nor night, it becomes day as Firmament Sage enters.
Whenever day becomes night or night becomes day, draw a card.

Hook-Haunt Drifter

Flying
If Hook-Haunt Drifter would be put into a graveyard from anywhere, exile it instead.

Baithook Angler

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

Baithook Angler // Hook-Haunt Drifter

Moonrager's Slash

This spell costs {2} less to cast if it's night.
Moonrager's Slash deals 3 damage to any target.

Waildrifter

Flying
If Waildrifter would be put into a graveyard from anywhere, exile it instead.

Galedrifter

Flying
Disturb {4}{U} (You may cast this card from your graveyard transformed for its disturb cost.)