The rolled up wing of a Faerie Dragon, which only remains intact if it was given willingly, turned into a quill and infused with several enchantments.  This quill fuels the wielder's hunger for arcane knowledge.

When attuned, this quill vibrates very gently.  This quill can be used as an Arcane focus and has 5 charges.  When a spell on the Wizard spell list is cast from a location the wielder can see then the user can use their reaction to use a charge and roll a d10.  On a 1-6, the spell goes off as normal and nothing happens.  On a 7-9 then the quill begins to store knowledge of the spell.  On a 10 the quill gains perfect knowledge of the spell.  If the spell is of a level that the wielder can cast then they can choose to burn a number of charges equal to the level of the spell in order to cancel the original spell and instantly cast it without using a spell slot.  The quill regains 1d4+1 charges at Dawn.

This quill can store knowledge of up to three spells.  To gain perfect knowledge of a spell the quill must store knowledge 4 times, unless the wielder rolls a 10 to instantly gain full knowledge.  Once the quill has perfect knowledge of a spell the wielder can use it to scribe the spell into their spellbook.  The wielder must still spend the requisite time and gold to scribe the spell, but do not need a spell scroll to copy.  If the wielder wants to replace a spell they must remove the old spell by spending one minute at the end of a short or long rest communing with the quill to remove it.

Notes: Magic Item Name - The Spell Snitch Quill, Requires Attiunement - True, Attunement Description - by a wizard