Crimson Lash

As part of casting this spell, you must take 1d6 necrotic damage. This damage can not be lowered or negated in anyway.

This magic weapon lasts until the spell ends. It counts as a simple weapon with which you are proficient, and it has the light, finesse, and reach properties. You can choose to add your spellcasting modifier, instead of your Strength or Dexterity modifier, to attack and damage rolls with this weapon. Its damage die is 1d6, and the damage dealt is necrotic. Each time a creature takes damage from this magic weapon, its maximum hit points are reduced by an amount equal to the damage it took.