Tasha's Hideous Laughter

Each opponent exiles cards from the top of their library until that player has exiled cards with total mana value 20 or more.

Jace, the Perfected Mind

Compleated ({U/P} can be paid with {U} or 2 life. If life was paid, this planeswalker enters with two fewer loyalty counters.)
+1: Until your next turn, up to one target creature gets -3/-0.
−2: Target player mills three cards. Then if a graveyard has twenty or more cards in it, you draw three cards. Otherwise, you draw a card.
−X: Target player mills three times X cards.

Into the Story

This spell costs {3} less to cast if an opponent has seven or more cards in their graveyard.
Draw four cards.

Ipnu Rivulet

{T}: Add {C}.
{T}, Pay 1 life: Add {U}.
{1}{U}, {T}, Sacrifice a Desert: Target player mills four cards. (They put the top four cards of their library into their graveyard.)

Fading Hope

Return target creature to its owner's hand. If its mana value was 3 or less, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Maddening Cacophony

Kicker {3}{U}
Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard Otawara, Soaring City: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

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.)

Island

Jwari Ruins

Jwari Disruption

Counter target spell unless its controller pays {1}.

Jwari Disruption // Jwari Ruins

Drowned Secrets

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

Scavenger Grounds

{T}: Add {C}.
{2}, {T}, Sacrifice a Desert: Exile all graveyards.

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)