Clever Lumimancer

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

Ashmouth Dragon

Flying
Whenever you cast an instant or sorcery spell, this creature deals 2 damage to any target.

Smoldering Egg

Defender
Whenever you cast an instant or sorcery spell, put a number of ember counters on this creature equal to the amount of mana spent to cast that spell. Then if this creature has seven or more ember counters on it, remove them and transform this creature.

Smoldering Egg // Ashmouth Dragon

Monastery Mentor

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, create a 1/1 white Monk creature token with prowess.

Insectile Aberration

Delver of Secrets

At the beginning of your upkeep, look at the top card of your library. You may reveal that card. If an instant or sorcery card is revealed this way, transform this creature.

Delver of Secrets // Insectile Aberration

Dreadhorde Arcanist

Trample
Whenever this creature attacks, you may cast target instant or sorcery card with mana value less than or equal to this creature's power from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.