Wondrous Item

Rare Requires Attunement

This skull shaped device is filled with knowledge.
The device weighs 5 pounds and is covered with subtle etchings of planar sigils.
As a bonus action, you can toss the device into the air, whereupon it floats at a distance of 1d3 feet from you and you can access its properties. While the mimir is floating, a creature other than you can use an action to grasp or net the device, either by making a successful unarmed strike against AC 22 or a successful DC 22 Dexterity (Acrobatics) check. You can use a bonus action to seize and stow the device.
The device has AC 22, 25 hit points, immunity to poison and psychic damage, and resistance to all other damage. It is considered to be an object that is worn while it is floating near you.
Esoteric Knowledge: While the device is floating, you can use an action to cast Legend Lore from the device. The device speaks the revealed lore aloud. Once this property has been used, it can't be used again until the next dawn.
Planar Knowledge: The device knows basic, useful information about the planes of existence. While the device is floating, it verbally answers questions you or anyone you designate poses to it about that topic. It knows the information about the planes in the Dungeon Master's Guide, as well as basic information about the gate-towns of the Outlands.

Cost: 501 gp - 5,000 gp