Innate Spellcasting The Hellshriek's innate spellcasting ability is Charisma (spell save DC 15, +7 to hit with spell attacks). It can innately cast the following spells:   Firebolt (at will)
Haste (2 per day)]br] Wall of Fire (1 per day)

Mist Form
The Hellshriek can use an action to turn itself into a shadowy mist, becomming immune to all attacks and has advantage on Strength, Dexterity, and Constitution saving throws, and it is immune to nonmagical damage. It is able to move itself up to 50 ft, through small holes, narrow openings, and even mere cracks, though it treats liquids as though they were solid surfaces. It can't fall and remains hovering in the air even when stunned or otherwise incapacitated.   While in the form of a misty cloud, the target can't talk or manipulate objects, and any objects it was carrying or holding can't be dropped, used, or otherwise interacted with. The target can't attack or cast spells.   Hellish Screech
As an action the Hellshriek can let loose a terrifying screech, causing those within a 60 ft cone to make a DC 14 Wisdom save, taking 16 ( 3d10 ) phsychic damage on a fail, half as much on a success.