Tzaangor Shaman

Flying
Sorcerous Elixir — Whenever Tzaangor Shaman deals combat damage to a player, copy the next instant or sorcery spell you cast this turn when you cast it. You may choose new targets for the copy.

Mischievous Chimera

Flying
Whenever you cast your first spell during each opponent's turn, Mischievous Chimera deals 1 damage to each opponent. Scry 1.

Spectacle Mage

Flying
Instant and sorcery spells you cast with mana value 5 or greater cost {1} less to cast.

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.

Kaza, Roil Chaser

Flying, haste
{T}: The next instant or sorcery spell you cast this turn costs {X} less to cast, where X is the number of Wizards you control as this ability resolves.

Kraum, Violent Cacophony

Flying
Whenever you cast your second spell each turn, put a +1/+1 counter on Kraum, Violent Cacophony and draw a card.

Maelstrom Muse

Flying
Whenever Maelstrom Muse attacks, the next instant or sorcery spell you cast this turn costs {X} less to cast, where X is Maelstrom Muse's power as this ability resolves.

League Guildmage

{3}{U}, {T}: Draw a card.
{X}{R}, {T}: Copy target instant or sorcery spell you control with mana value X. You may choose new targets for the copy.

Storm Skreelix

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, Storm Skreelix gets +2/+0 until end of turn.

Ovika, Enigma Goliath

Flying
Ward—{3}, Pay 3 life.
Whenever you cast a noncreature spell, create X 1/1 red Phyrexian Goblin creature tokens, where X is the mana value of that spell. They gain haste until end of turn.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Wee Dragonauts

Flying
Whenever you cast an instant or sorcery spell, Wee Dragonauts gets +2/+0 until end of turn.

Party Thrasher

Noncreature spells you cast from exile have convoke. (Each creature you tap while casting a noncreature spell from exile pays for {1} or one mana of that creature's color.)
At the beginning of your first main phase, you may discard a card. If you do, exile the top two cards of your library, then choose one of them. You may play that card this turn.

Stella Lee, Wild Card

Whenever you cast your second spell each turn, exile the top card of your library. Until the end of your next turn, you may play that card.
{T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy. Activate only if you've cast three or more spells this turn.

Mizzix of the Izmagnus

Whenever you cast an instant or sorcery spell with mana value greater than the number of experience counters you have, you get an experience counter.
Instant and sorcery spells you cast cost {1} less to cast for each experience counter you have.

Goblin Electromancer

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

Pink Horror

Coruscating Flames — Whenever you cast an instant or sorcery spell, Pink Horror deals 2 damage to any target.
Split — When Pink Horror dies, create two 2/2 blue and red Demon Horror creature tokens named Blue Horror with "Whenever you cast an instant or sorcery spell, this creature deals 1 damage to any target."

Battlefield Thaumaturge

Each instant and sorcery spell you cast costs {1} less to cast for each creature it targets.
Heroic — Whenever you cast a spell that targets Battlefield Thaumaturge, Battlefield Thaumaturge gains hexproof until end of turn.

Tempest Trapper

{T}: Add two mana in any combination of colors. Spend this mana only to cast instant or sorcery spells.
Whenever you cast your third spell each turn, exile a random card from your library. Until end of turn, you may play that card without paying its mana cost.

Aegar, the Freezing Flame

Whenever a creature or planeswalker an opponent controls is dealt excess damage, if a Giant, Wizard, or spell you controlled dealt damage to it this turn, draw a card.

Gelectrode

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

Academy Loremaster

At the beginning of each player's draw step, that player may draw an additional card. If they do, spells they cast this turn cost {2} more to cast.

Adeliz, the Cinder Wind

Flying, haste
Whenever you cast an instant or sorcery spell, Wizards you control get +1/+1 until end of turn.

Hypersonic Dragon

Flying, haste
You may cast sorcery spells as though they had flash. (You may cast them any time you could cast an instant.)

Razzle-Dazzler

Whenever you cast your second spell each turn, put a +1/+1 counter on Razzle-Dazzler. It can't be blocked this turn.

Magus of the Future

Play with the top card of your library revealed.
You may play lands and cast spells from the top of your library.

Johann, Apprentice Sorcerer

You may look at the top card of your library any time.
Once each turn, you may cast an instant or sorcery spell from the top of your library. (You still pay its costs. Timing rules still apply.)

Rockslide Sorcerer

Whenever you cast an instant, sorcery, or Wizard spell, Rockslide Sorcerer deals 1 damage to any target.

Alania, Divergent Storm

Whenever you cast a spell, if it's the first instant spell, the first sorcery spell, or the first Otter spell other than Alania you've cast this turn, you may have target opponent draw a card. If you do, copy that spell. You may choose new targets for the copy.

Omnispell Adept

{2}{U}, {T}: You may cast an instant or sorcery spell from your hand without paying its mana cost.

Najal, the Storm Runner

You may cast sorcery spells as though they had flash.
Whenever Najal, the Storm Runner attacks, you may pay {2}. If you do, when you next cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.

Zaffai, Thunder Conductor

Magecraft — Whenever you cast or copy an instant or sorcery spell, scry 1. If that spell's mana value is 5 or greater, create a 4/4 blue and red Elemental creature token. If that spell's mana value is 10 or greater, Zaffai, Thunder Conductor deals 10 damage to an opponent chosen at random.

Tempest Angler

Whenever you cast a noncreature spell, put a +1/+1 counter on Tempest Angler.

Melek, Izzet Paragon

Play with the top card of your library revealed.
You may cast instant and sorcery spells from the top of your library.
Whenever you cast an instant or sorcery spell from your library, copy it. You may choose new targets for the copy.

Stormcatch Mentor

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Instant and sorcery spells you cast cost {1} less to cast.

Arjun, the Shifting Flame

Flying
Whenever you cast a spell, put the cards in your hand on the bottom of your library in any order, then draw that many cards.

Beamsplitter Mage

Whenever you cast an instant or sorcery spell that targets only Beamsplitter Mage, if you control one or more other creatures that spell could target, choose one of those creatures. Copy that spell. The copy targets the chosen creature.