Leonin Lightscribe

Magecraft — Whenever you cast or copy an instant or sorcery spell, creatures you control get +1/+1 until end of turn.

Quirion Beastcaller

Whenever you cast a creature spell, put a +1/+1 counter on Quirion Beastcaller.
When Quirion Beastcaller dies, distribute X +1/+1 counters among any number of target creatures you control, where X is the number of +1/+1 counters on Quirion Beastcaller.

Stormchaser Drake

Flying
Whenever Stormchaser Drake becomes the target of a spell you control, draw a card.

Tenth District Legionnaire

Haste
Whenever you cast a spell that targets Tenth District Legionnaire, put a +1/+1 counter on Tenth District Legionnaire, then scry 1.

Electrostatic Infantry

Trample
Whenever you cast an instant or sorcery spell, put a +1/+1 counter on Electrostatic Infantry.

Sprite Dragon

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

Monastery Swiftspear

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

Clever Lumimancer

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