Firespitter Whelp

Flying
Whenever you cast a noncreature or Dragon spell, this creature deals 1 damage to each opponent.

Crackling Cyclops

Whenever you cast a noncreature spell, this creature gets +3/+0 until end of turn.

Coruscation Mage

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Rabbit Battery

Haste
Equipped creature gets +1/+1 and has haste.
Reconfigure {R} ({R}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Thermo-Alchemist

Defender
{T}: This creature deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap this creature.

Veyran, Voice of Duality

Magecraft — Whenever you cast or copy an instant or sorcery spell, Veyran gets +1/+1 until end of turn.
If you casting or copying an instant or sorcery spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Heartfire Immolator

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
{R}, Sacrifice this creature: It deals damage equal to its power to target creature or planeswalker.

Pyroceratops

Trample
Whenever you cast a noncreature spell, put a +1/+1 counter on this creature.

Whiskerquill Scribe

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, you may discard a card. If you do, draw a card.

Strago and Relm

Sketch and Lore — {2}{R}, {T}: Target opponent exiles cards from the top of their library until they exile an instant, sorcery, or creature card. You may cast that card without paying its mana cost. If you cast a creature spell this way, it gains haste and "At the beginning of the end step, sacrifice this creature." Activate only as a sorcery.

Kindlespark Duo

{T}: This creature deals 1 damage to target opponent.
Whenever you cast a noncreature spell, untap this creature.

Emberheart Challenger

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, exile the top card of your library. Until end of turn, you may play that card.

Festival Crasher

Whenever you cast an instant or sorcery spell, this creature gets +2/+0 until end of turn.

Heartfire Hero

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, put a +1/+1 counter on it.
When this creature dies, it deals damage equal to its power to each opponent.

Hearthborn Battler

Haste
Whenever a player casts their second spell each turn, this creature deals 2 damage to target opponent.

Firebrand Archer

Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Devoted Duelist

Haste
Flurry — Whenever you cast your second spell each turn, this creature deals 1 damage to each opponent.

Harnesser of Storms

Whenever you cast a noncreature or Otter spell, you may exile the top card of your library. Until end of turn, you may play that card. This ability triggers only once each turn.

Sawblade Scamp

Haste
Whenever you cast a noncreature spell, put an oil counter on this creature.
{T}, Remove an oil counter from this creature: It deals 1 damage to each opponent.

Stormsplitter

Haste
Whenever you cast an instant or sorcery spell, create a token that's a copy of this creature. Exile that token at the beginning of the next end step.