Casting this spell deals an amount of damage to you equal to double a bladed weapon of your choice you are holding + the slot level used to cast this spell. This damage is dealt to you again for each creature that is being targeted, to a maximum of 3. When doing so, you add your Constitution modifier to the damage instead of Strength or Dexterity.   Make a small cut upon your arm, and choose up to three creature within range. You and the chosen creatures' blood is swapped, causing them to feel your viscous wrath within their own veins. The target creatures must make a Constitution saving throw, on a failure taking 8d8 fire damage as their blood boils inside of them, or half as much on a successful one.