Whip of the Master

You draw upon the Plane of Negative Energy, forming a vicious, shadowy whip in your right hand. Attacking with the whip counts as a melee spell attack. On a hit, the target takes 4d8 necrotic damage, and must make a wisdom saving throw or be frightened of you until the start of your next turn. Your attacks ignore physical objects in their path (cover is ignored and non-magic armor is not added to your target's AC). On a successful hit, the target must make a Constitution saving throw or gain 1 level of exhaustion. 

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d8 for each slot level above 6th.