Dreadwaters

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

Cut Your Losses

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Target player mills half their library, rounded down.

Twenty-Toed Toad

Your maximum hand size is twenty.
Whenever you attack with two or more creatures, put a +1/+1 counter on Twenty-Toed Toad and draw a card.
Whenever Twenty-Toed Toad attacks, you win the game if there are twenty or more counters on it or you have twenty or more cards in hand.

Drown in Dreams

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Target player draws X cards.
• Target player mills twice X cards.

Court of Cunning

When Court of Cunning enters, you become the monarch.
At the beginning of your upkeep, any number of target players each mill two cards. If you're the monarch, each of those players mills ten cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Cloudhoof Kirin

Flying
Whenever you cast a Spirit or Arcane spell, you may have target player mill X cards, where X is that spell's mana value.

Didn't Say Please

Counter target spell. Its controller mills three cards.

Broken Ambitions

Counter target spell unless its controller pays {X}. Clash with an opponent. If you win, that spell's controller mills four cards. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Dreamborn Muse

At the beginning of each player's upkeep, that player mills X cards, where X is the number of cards in their hand.

Drowner Initiate

Whenever a player casts a blue spell, you may pay {1}. If you do, target player mills two cards.

Dampen Thought

Target player mills four cards.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Brain Freeze

Target player mills three cards.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Kami of the Crescent Moon

At the beginning of each player's draw step, that player draws an additional card.

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Chronic Flooding

Enchant land
Whenever enchanted land becomes tapped, its controller mills three cards.

Countermand

Counter target spell. Its controller mills four cards.

Archive Trap

If an opponent searched their library this turn, you may pay {0} rather than pay this spell's mana cost.
Target opponent mills thirteen cards.