Mana Leak

Counter target spell unless its controller pays {3}.

Experimental Overload

Create an X/X blue and red Weird creature token, where X is the number of instant and sorcery cards in your graveyard. Then you may return an instant or sorcery card from your graveyard to your hand. Exile Experimental Overload.

Roaming Ghostlight

Flying
When Roaming Ghostlight enters, return up to one target non-Spirit creature to its owner's hand.

Skewer the Critics

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Skewer the Critics deals 3 damage to any target.

Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Gelectrode

{T}: Gelectrode deals 1 damage to any target.
Whenever you cast an instant or sorcery spell, you may untap Gelectrode.

Crackling Drake

Flying
Crackling Drake's power is equal to the total number of instant and sorcery cards you own in exile and in your graveyard.
When Crackling Drake enters, draw a card.

Maritime Guard

Lightning Strike

Lightning Strike deals 3 damage to any target.

Goblin Arsonist

When Goblin Arsonist dies, you may have it deal 1 damage to any target.

Nivix Cyclops

Defender
Whenever you cast an instant or sorcery spell, Nivix Cyclops gets +3/+0 until end of turn and can attack this turn as though it didn't have defender.

Teleportal

Target creature you control gets +1/+0 until end of turn and can't be blocked this turn.
Overload {3}{U}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Island

Light Up the Stage

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Unsummon

Return target creature to its owner's hand.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Scorched Rusalka

{R}, Sacrifice a creature: Scorched Rusalka deals 1 damage to target player or planeswalker.

Mountain

Divination

Swiftwater Cliffs

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {R}.

Leyline of Lightning

If Leyline of Lightning is in your opening hand, you may begin the game with it on the battlefield.
Whenever you cast a spell, you may pay {1}. If you do, Leyline of Lightning deals 1 damage to target player or planeswalker.

Prismari Campus

Prismari Campus enters tapped.
{T}: Add {U} or {R}.
{4}, {T}: Scry 1.

Izzet Guildgate

This land enters tapped.
{T}: Add {U} or {R}.

Thunderous Wrath

Thunderous Wrath deals 5 damage to any target.
Miracle {R} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Mystic Monastery

Mystic Monastery enters tapped.
{T}: Add {U}, {R}, or {W}.

Coral Merfolk

Treasure Hunt

Reveal cards from the top of your library until you reveal a nonland card, then put all cards revealed this way into your hand.