Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.

Red Sun's Zenith

Red Sun's Zenith deals X damage to any target. If a creature dealt damage this way would die this turn, exile it instead. Shuffle Red Sun's Zenith into its owner's library.

Island

Blue Sun's Twilight

Gain control of target creature with mana value X or less. If X is 5 or more, create a token that's a copy of that creature.

Prismari Pledgemage

Defender
Magecraft — Whenever you cast or copy an instant or sorcery spell, Prismari Pledgemage can attack this turn as though it didn't have defender.

River Song

Meet in Reverse — You draw cards from the bottom of your library rather than the top.
Spoilers — Whenever an opponent scries, surveils, or searches their library, put a +1/+1 counter on River Song. Then River Song deals damage to that player equal to its power.

Niv-Mizzet, the Firemind

Flying
Whenever you draw a card, Niv-Mizzet, the Firemind deals 1 damage to any target.
{T}: Draw a card.

Lightning Stormkin

Flying
Haste (This creature can attack and {T} as soon as it comes under your control.)

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Timestream Navigator

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
{2}{U}{U}, {T}, Put Timestream Navigator on the bottom of its owner's library: Take an extra turn after this one. Activate only if you have the city's blessing.

Niv-Mizzet, Dracogenius

Flying
Whenever Niv-Mizzet, Dracogenius deals damage to a player, you may draw a card.
{U}{R}: Niv-Mizzet, Dracogenius deals 1 damage to any target.

Izzet Cluestone

{T}: Add {U} or {R}.
{U}{R}, {T}, Sacrifice Izzet Cluestone: Draw a card.

Gitaxian Spellstalker

Trample, ward {2}, prowess, prowess (Each instance of prowess triggers separately.)

Khenra Spellspear

Trample
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
{3}{U/P}: Transform Khenra Spellspear. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

Khenra Spellspear // Gitaxian Spellstalker

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Balmor, Battlemage Captain

Flying
Whenever you cast an instant or sorcery spell, creatures you control get +1/+0 and gain trample until end of turn.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Mountain

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

City on Fire

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
If a source you control would deal damage to a permanent or player, it deals triple that damage instead.

Izzet Locket

{T}: Add {U} or {R}.
{U/R}{U/R}{U/R}{U/R}, {T}, Sacrifice Izzet Locket: Draw two cards.

Izzet Boilerworks

Izzet Boilerworks enters the battlefield tapped.
When Izzet Boilerworks enters the battlefield, return a land you control to its owner's hand.
{T}: Add {U}{R}.

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Red Sun's Twilight

Destroy up to X target artifacts. If X is 5 or more, for each artifact destroyed this way, create a token that's a copy of it. Those tokens gain haste. Exile them at the beginning of the next end step.

Vessel of Volatility

{1}{R}, Sacrifice Vessel of Volatility: Add {R}{R}{R}{R}.

Teferi's Puzzle Box

At the beginning of each player's draw step, that player puts the cards in their hand on the bottom of their library in any order, then draws that many cards.

Izzet Keyrune

{T}: Add {U} or {R}.
{U}{R}: Until end of turn, Izzet Keyrune becomes a 2/1 blue and red Elemental artifact creature.
Whenever Izzet Keyrune deals combat damage to a player, you may draw a card. If you do, discard a card.

Sprite Dragon

Flying, haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Sprite Dragon.

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. Talisman of Creativity deals 1 damage to you.

Compleated Conjurer

When this creature transforms into Compleated Conjurer, exile the top card of your library. Until the end of your next turn, you may play that card.

Captive Weird

Defender
{3}{R/P}: Transform Captive Weird. Activate only as a sorcery. ({R/P} can be paid with either {R} or 2 life.)