Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Flip the Switch

Counter target spell unless its controller pays {4}. Create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Sludge Monster

Whenever this creature enters or attacks, put a slime counter on up to one other target creature.
Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Phantom Carriage

Flying
When this creature enters, you may search your library for a card with flashback or disturb, put it into your graveyard, then shuffle.

Lanterns' Lift

Enchant creature
Enchanted creature gets +1/+1 and has flying.
If Lanterns' Lift would be put into a graveyard from anywhere, exile it instead.

Lantern Bearer

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

Lantern Bearer // Lanterns' Lift

Fading Hope

Return target creature to its owner's hand. If its mana value was 3 or less, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Falcon Abomination

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

Firmament Sage

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

Skaab Wrangler

Tap three untapped creatures you control: Tap target creature.

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.

Archive Haunt

Flying
Whenever this creature attacks, draw a card, then discard a card.
If Archive Haunt would be put into a graveyard from anywhere, exile it instead.

Overwhelmed Archivist

When this creature enters, draw a card, then discard a card.
Disturb {3}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Overwhelmed Archivist // Archive Haunt

Ominous Roost

When this enchantment enters and whenever you cast a spell from your graveyard, create a 1/1 blue Bird creature token with flying and "This token can block only creatures with flying."

Island

Revenge of the Drowned

Target creature's owner puts it on their choice of the top or bottom of their library. You create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

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.)

Unblinking Observer

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

Vivisection

As an additional cost to cast this spell, sacrifice a creature.
Draw three cards.

Cobbled Lancer

As an additional cost to cast this spell, exile a creature card from your graveyard.
{3}{U}, Exile this card from your graveyard: Draw a card.

Locked in the Cemetery

Enchant creature
When this Aura enters, if there are five or more cards in your graveyard, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Organ Hoarder

When this creature enters, look at the top three cards of your library, then put one of them into your hand and the rest into your graveyard.