Blood Cyst

You attempt to create a blood-filled cyst in the body of a creature within range that has a vascular system. The target must make a Constitution saving throw. If it fails, a blood cyst forms within the target, and it has disadvantage on saving throws against necromancy spells. The growth is visible under the skin and you determine where the cyst resides. Given 1 hour, a creature that has proficiency with a healer's kit can remove the cyst.