Elementalist Adept

Flash (You may cast this spell any time you could cast an instant.)
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Dimir Locket

{T}: Add {U} or {B}.
{U/B}{U/B}{U/B}{U/B}, {T}, Sacrifice Dimir Locket: Draw two cards.

Faerie Invaders

Flash (You may cast this spell any time you could cast an instant.)
Flying

Daring Thunder-Thief

Flash
Daring Thunder-Thief enters tapped.

Essence Scatter

Unfathomable Truths

Devoid (This card has no color.)
Draw three cards and create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this creature: Add {C}."

Naiad of Hidden Coves

During turns other than yours, spells you cast cost {1} less to cast.

Island

Quick Study

Vexing Gull

Out of Air

This spell costs {2} less to cast if it targets a creature spell.
Counter target spell.

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Mantle of Tides

Equipped creature gets +1/+2.
Whenever you draw your second card each turn, attach Mantle of Tides to target creature you control.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Aven Reedstalker

Case the Joint

Draw two cards, then look at the top card of each player's library.

Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

Undersea Invader

Flash (You may cast this spell any time you could cast an instant.)
Undersea Invader enters tapped.

Refute

Counter target spell. Draw a card, then discard a card.

Faerie Duelist

Flash
Flying
When Faerie Duelist enters, target creature an opponent controls gets -2/-0 until end of turn.

Brinebarrow Intruder

Flash
When Brinebarrow Intruder enters, target creature an opponent controls gets -2/-0 until end of turn.

Geyser Drake

Flying
During turns other than yours, spells you cast cost {1} less to cast.

Run Away Together

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.