Indelible Pen

Wondrous Item, Common
An simple, innocuous inkpen with a permanently stained nib, which feels uncomfortably cold to the touch and upon close inspection appears to be crafted from bone.
This pen can write on any surface, never requires new ink, and what it writes cannot be erased by any means short of destroying the marked surface. As an action you can use this pen to scribe one spell scroll for free. The spell scribed must be of a level no higher than your Proficiency Bonus. Once you've done so you cannot do so again until a number of days have passed equal to the number of days it would normally take to scribe the scroll (see the Spell Scroll Costs chart in the Player's Handbook.)