Aspect of the Infernal

Grow red devil's tail which could be used as an attack on a bonus action.  To hit is the caster's spell attack and damage will be 2d6 + spell damage modifier slashing damage.  (This attack will be considered magical for the purposes of overcoming immunity to non-magical attacks.)

Grow red leathery wings giving a flight speed of 60 feet for the spell's duration.

Gain the ability to see in both magical and non-magical darkness.

Gain immunity to fire and poison damage.

Gain advantage on saving throws against spells.