Slip Out the Back

Put a +1/+1 counter on target creature. It phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Haughty Djinn

Flying
Haughty Djinn's power is equal to the number of instant and sorcery cards in your graveyard.
Instant and sorcery spells you cast cost {1} less to cast.

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 Delver of Secrets.

Delver of Secrets // Insectile Aberration

Stormchaser Drake

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

Twinferno

Choose one —
• When you cast your next instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
• Target creature you control gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
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.

Electrostatic Infantry

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