Approaching Storm

A localized tempest of dark clouds, crackling blue lightning, and phantom blades swirls around you. For the duration, the area within 10 feet of you is difficult terrain for your enemies. When a creature enters the area for the first time on a turn or starts its turn there, it must make a Dexterity saving throw. It takes 1d6 lightning damage on a failed save. 

At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.