Wall of Lost Thoughts

Defender (This creature can't attack.)
When Wall of Lost Thoughts enters, target player mills four cards. (They put the top four cards of their library into their graveyard.)

Draugr Thought-Thief

When Draugr Thought-Thief enters, look at the top card of target player's library. You may put that card into their graveyard.

Deep Analysis

Target player draws two cards.
Flashback—{1}{U}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Towering-Wave Mystic

Whenever Towering-Wave Mystic deals damage, target player mills that many cards.

Island

Waker of Waves

Creatures your opponents control get -1/-0.
{1}{U}, Discard Waker of Waves: Look at the top two cards of your library. Put one of them into your hand and the other into your graveyard.

Neerdiv, Devious Diver

Whenever Neerdiv, Devious Diver becomes tapped, target player mills cards equal to its power.
Whenever you cast a spell from your graveyard or activate an ability of a card in your graveyard, draw a card and put a +1/+1 counter on Neerdiv.

Thriving Isle

Thriving Isle enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Sudden Insight

Draw a card for each different mana value among nonland cards in your graveyard.

Cruel Witness

Flying
Whenever you cast a noncreature spell, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Expendable Lackey

{1}{U}, Exile Expendable Lackey from your graveyard: Create a 1/1 blue Fish creature token with "This creature can't be blocked." Activate only as a sorcery.

Locked in the Cemetery

Enchant creature
When Locked in the Cemetery 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.

Screaming Swarm

Flying
Whenever you attack with one or more creatures, target player mills that many cards. (To mill a card, a player puts the top card of their library into their graveyard.)
{2}{U}: Put Screaming Swarm from your graveyard into your library second from the top.

Cackling Counterpart

Create a token that's a copy of target creature you control.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)