Death Ray

Cast (Action) (Instantaneous): You emit a pale green ray to make a blast attack (see Blast Attacks) against a creature or an object within 60 squares of you. You have advantage on the Fighting test. If you succeed, the target takes necrotic damage equal to twice your result.

If this damage leaves a creature -- other than a Construct or Undead (see Creature Types) -- with 0 hit points, its body is reduced to ash (leaving behind only its clothing and equipment).

Once you have cast Death Ray, you must finish a long rest before you can cast it again.