Tome Scour

Frost Breath

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

Wall of Runes

Defender (This creature can't attack.)
When this creature enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Claustrophobia

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Island

Trail of Evidence

Whenever you cast an instant or sorcery spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Urza's Rebuff

Choose one —
• Counter target spell.
• Tap up to two target creatures.

Lost in the Mist

Counter target spell. Return target permanent to its owner's hand.

Wall of Air

Defender, flying (This creature can't attack, and it can block creatures with flying.)

Wall of Mist

Keening Stone

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

So Tiny

Flash
Enchant creature
Enchanted creature gets -2/-0. It gets -6/-0 instead as long as its controller has seven or more cards in their graveyard.

Caelorna, Coral Tyrant

Fleeting Memories

When this enchantment enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, target player mills three cards.

Countermand

Counter target spell. Its controller mills four cards.

Dream Twist

Target player mills three cards.
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Shriekgeist

Flying
Whenever this creature deals combat damage to a player, that player mills two cards.

Glacial Wall

Compelling Argument

Target player mills five cards.
Cycling {U} ({U}, Discard this card: Draw a card.)

Nivix Barrier

Flash (You may cast this spell any time you could cast an instant.)
Defender (This creature can't attack.)
When this creature enters, target attacking creature gets -4/-0 until end of turn.

Ichthyomorphosis

Enchant creature
Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1.

Riptide Turtle

Mnemonic Wall

Defender
When this creature enters, you may return target instant or sorcery card from your graveyard to your hand.

Doorkeeper

Defender
{2}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender.

Mind Sculpt

Belltower Sphinx

Flying
Whenever a source deals damage to this creature, that source's controller mills that many cards.