Annihilate

You release 4 beams of solid darkness, 5 feet wide and 1000 feet long, in any direction you chose.  Any creature in the path of a beam must make a constitution saving throw or take 5d6 necrotic, and 5d6 Force damagee.  On a susessful save, the target takes half damage.  When 2 or more beams overlap, both the damage and the beam width stack.  A creature in the path of more than 1 beam makes only 1 saving throw.  Nonliving objects, not worn by a creature, automatically fail their save but take the force damage only.   Any creature reduced to 0 hit points is annihilated.