Wiltwood's Woeful Wither Word

You speak a word or phrase that evokes the absolution of entropy to a single target creature within range, causing immense physical and psychological pain. The target creature must make a Wisdom saving throw. On a failed save the target must take 3d6 Necrotic damage and 3d6 Psychic damage, and begin feel an internal withering. The internal withering  gives the target creature disadvantage on the next constitution saving throw, including concentration checks, made before the end of the casters next turn. On a Successful save the target takes half damage and does not suffer the withering feeling.

If the target creature understands or speaks the language the word or phrase is spoken in, it must make the save at disadvantage. A creature that does not understand the language the word or phrase is spoken in, or is deafened, it automatically saves.

At higher levels. When you cast this spell at 5th level or higher increase the damage by 1d6 necrotic and 1d6 psychic for each spell slot level above 4th.