Vapor Cloud

The caster’s hand points at a targeted space(similar in appearance as if the sith were to strike you with lightning, but instead with a vapor cloud).  Out of the caster’s fingertips, a pure-black gas starts to ooze out.  It then pools at the bottom of the 5 ft circle.  Anything or any creature within the vicinity of the circle takes 4d6 necrotic damage and makes a constitution saving throw with a DC of Root Ability Modifier + Ability-Spell Bonus + Current Rank Bonus + 5.  Upon a failed saving throw, the being is engulfed with the shadowvapor and is “shadowed”, receiving 1d6 damage at the beginning of every turn they take.  The only way to “disable” this damage is to be healed or take a short or long rest.  Upon a critical hit, the “shadowed” damage is not doubled.