Mind Sliver

You drive a disorienting spike of psychic energy
into the mind of one creature you can see within
range. The target must succeed on an Intelligence
saving throw or take 1d6 psychic damage and
subtract 1d4 from the next saving throw it makes
before the end of your next turn.
Damage increases at 5th level (2d6), 11th level
(3d6), and 17th level (4d6).