Destructive Beam (Reworked)

You call fourth a red beam of powerful destructive energy, choose 1 creature within 80 feet of you to make a DEX save and they must take 6d8 necrotic damage or half on save. Before attacking you can also choose to sacrifice your own hp to empower the spell. You can increase the number of d8 used on this spell by spending 5 hp to add a die. You can add a max of 4 more dice. If you wish you can also shoot this beam in a cone of 40 ft. With this type of casting the d8 now does d6 but goes by all of the same rules otherwise.