Brainsucker

Dark tendrils leave the mouth of the caster and travel over to bind to the head of the target. 

The target must make a DC 15 Wisdom saving throw, or else be afflicted by the following condition until either the spell ends or the caster falls unconscious.

Dark Frenzy: The afflicted creature's damage output is halved, though they become immune to Psychic damage and resistant to all other types. The creature has disadvantage on all ability checks and saving throws. The creature cannot communicate coherently and can only mumble incoherently, shout or scream.