Arrow of Soul Reaping

When you hit a creature with this magic ammunition, a curdling wave of necrotic energy forces all creatures within 20 ft. of it to make a DC 17 Constitution saving throw. On a failed save, their maximum hit points is reduced by 6d8. On a successful save, they take 6d8 necrotic damage. If the maximum hit point reduction kills the target, you control the targets as suitable undead (GM's decision) for 1 hour. The maximum hit point reduction lasts until the end of their next long rest, if they survive.