Wand, very rare (requires attunement by spellcaster)
This wand has 7 charges. While holding it, you can use an action to expend 1 of its charges to cause a thin black ray to streak from the tip toward a creature you can see within 60 feet of you. Make a ranged attack roll against that creature using your spell attack bonus. On a hit, the target takes 2d6 necrotic damage and must succeed on a DC 12 Constitution saving throw. On a failed save, the target's hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. This wand has no effect on constructs or undead.
The wand regains 1d6 + 1 expended charges daily at dawn. If you expend the wand's last charge, roll a d20. On a 1, the wand crumbles into ashes and is destroyed.