Seal of Eternity (5e Equipment)

Staff (quarterstaff), artifact (requires attunement)

A golden staff with an inlay of ruby shavings, there is an empty filigree cage at the head. This staff grants a +3 bonus to your spell attack rolls and spellsave DC. Spells cast by an attuned creature on this staff persist indefinitely. Casting a new spell on this staff will replace the old one.

You may cast continual flame with this staff, without any costly material components.

It seems to be a key or source of power of some kind, but it's purpose and origin are unknown.

Proficiency with a Quarterstaff allows you to add your proficiency bonus to the attack roll for any attack you make with this weapon.