The Comfort of Nothingness

As an action, you can drive the blade into the ground (or point it forward), unleashing the "comfort" of the void. Each creature of your choice within 30 feet of you must make a Wisdom Saving Throw against your Warlock Spell Save DC. ​On a Failure: The creature takes 3d8 Psychic damage and is Restrained by heavy, shadowy tendrils until the end of your next turn. During this time, the creature is blinded and deafened, suspended in a pocket of absolute sensory deprivation (the void). ​On a Success: The creature takes half damage and is not restrained. ​Frequency: You can use this ability once per Short or Long Rest.