Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Dimir Doppelganger

{1}{U}{B}: Exile target creature card from a graveyard. Dimir Doppelganger becomes a copy of that card, except it has this ability.

Soulless Jailer

Permanent cards in graveyards can't enter the battlefield.
Players can't cast noncreature spells from graveyards or exile.

Hover Barrier

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.

Doomsday Excruciator

Flying
When Doomsday Excruciator enters, if it was cast, each player exiles all but the bottom six cards of their library face down.
At the beginning of your upkeep, draw a card.

Jace's Phantasm

Flying
Jace's Phantasm gets +4/+4 as long as an opponent has ten or more cards in their graveyard.

Manic Scribe

When Manic Scribe enters, each opponent mills three cards.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, that player mills three cards.

Phenax, God of Deception

Indestructible
As long as your devotion to blue and black is less than seven, Phenax isn't a creature.
Creatures you control have "{T}: Target player mills X cards, where X is this creature's toughness."

Mortivore

Mortivore's power and toughness are each equal to the number of creature cards in all graveyards.
{B}: Regenerate Mortivore. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

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.)

Corrupted Shapeshifter

Devoid (This card has no color.)
As Corrupted Shapeshifter enters, it becomes your choice of a 3/3 creature with flying, a 2/5 creature with vigilance, or a 0/12 creature with defender.

Wight of Precinct Six

Wight of Precinct Six gets +1/+1 for each creature card in your opponents' graveyards.

Keening Stone

{5}, {T}: Target player mills X cards, where X is the number of cards in that player's graveyard.

Wall of Frost

Defender
Whenever Wall of Frost blocks a creature, that creature doesn't untap during its controller's next untap step.

Avatar of Woe

If there are ten or more creature cards total in all graveyards, this spell costs {6} less to cast.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{T}: Destroy target creature. It can't be regenerated.

Ioreth of the Healing House

{T}: Untap another target permanent.
{T}: Untap two other target legendary creatures.