Solve the Equation

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Tezzeret the Seeker

+1: Untap up to two target artifacts.
−X: Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.
−5: Artifacts you control become artifact creatures with base power and toughness 5/5 until end of turn.

Mind Control

Enchant creature
You control enchanted creature.

Ghostform

Up to two target creatures can't be blocked this turn.

Displacement Wave

Return all nonland permanents with mana value X or less to their owners' hands.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Vectis Silencers

{2}{B}: This creature gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy that creature.)

Cloudfin Raptor

Flying
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Entrancing Melody

Gain control of target creature with mana value X.

Mind Flayer

Dominate Monster — When this creature enters, gain control of target creature for as long as you control this creature.

Reality Strobe

Return target permanent to its owner's hand. Exile Reality Strobe with three time counters on it.
Suspend 3—{2}{U} (Rather than cast this card from your hand, you may pay {2}{U} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Jace's Phantasm

Flying
This creature gets +4/+4 as long as an opponent has ten or more cards in their graveyard.

Relic's Roar

Until end of turn, target artifact or creature becomes a Dinosaur artifact creature with base power and toughness 4/3 in addition to its other types.

Island

Hydrosurge

Target creature gets -5/-0 until end of turn.

Cloud Sprite

Flying (This creature can't be blocked except by creatures with flying or reach.)
This creature can block only creatures with flying.

Time Stretch

Target player takes two extra turns after this one.

Inevitable Betrayal

Suspend 3—{1}{U}{U} (Rather than cast this card from your hand, pay {1}{U}{U} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Search target opponent's library for a creature card and put that card onto the battlefield under your control. Then that player shuffles.

Mindshrieker

Flying
{2}: Target player mills a card. This creature gets +X/+X until end of turn, where X is the milled card's mana value.