[Variant] Vitality Mirror (Patreon)

Wondrous item, uncommon

This metallic syringe is attached to a clear translucent opal with a divination rune carved into it. Queen Quintilla requested its creation when her son Prince Glinsmith went to fight in the Marshes War. It has a complex encantation that allows it to connect to a target on the same plane of existence using its own blood as a catalyst.

As a bonus action, you can use this magic syringe to remove a small amount of blood from a willing creature. The creature takes 1 necrotic damage. This damage can't be reduced in any way. As long as this magic item remains active, the creature's hit point maximum is decreased by the amount of necrotic damage taken, and the Opal becomes vivid red.

As long as the creature and the Vitality Mirror are on the same plane of existence, a dark mist begins to consume the Opal whenever the creature takes damage. As the creature's Hit Points lowers, the Opal turns darker. If the creature recovers, the mist dissipates, and the Opal returns to its vivid red color.