Helm of Darkness

Wondrous Item, legendary (requires attunement)

This black helm belonging to Hades is said to make its wearer invisible. While attuned to this item the wearer can take 1 minute to concentrate and cast the invisibility spell. The wearer also gains the ability to see through nonmagical and magical darkness for up to 90 feet, and become resistant to necrotic damage.

In addition , the wearer can cast create undead at 9th level through the helm. This ability can only be used once per long rest.