Taigam's Scheming

Surveil 5. (Look at the top five cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Drowned Secrets

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

Contingency Plan

Codex Shredder

{T}: Target player mills a card. (They put the top card of their library into their graveyard.)
{5}, {T}, Sacrifice Codex Shredder: Return target card from your graveyard to your hand.

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.

Cephalid Vandal

At the beginning of your upkeep, put a shred counter on Cephalid Vandal. Then mill a card for each shred counter on Cephalid Vandal.

Curse of the Bloody Tome

Enchant player
At the beginning of enchanted player's upkeep, that player mills two cards.

Cathartic Adept

Deranged Assistant

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Perfected Form

Aberrant Researcher

Flying
At the beginning of your upkeep, mill a card. If an instant or sorcery card was milled this way, transform Aberrant Researcher.

Aberrant Researcher // Perfected Form

Compelling Argument

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

Octavia, Living Thesis

This spell costs {8} less to cast if you have eight or more instant and/or sorcery cards in your graveyard.
Ward {8}
Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature has base power and toughness 8/8 until end of turn.

Chronic Flooding

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