Source Awareness

You have an acute awareness of the flow of magical energy. When a spell is cast within a number of feet of you equal to your passive Perception score × 10 feet, you are aware of the general direction from which the spell is cast, as well as the level of the spell. You may use a bonus action to make an Intelligence (Arcana) check (DC = 10 + the spell’s level). If successful, you recognize the school of the triggering spell.