Badge of the Savant

A badge of the savant is a platinum bookplate that can be magically affixed to a spellbook. Each badge features a design that represents a different school of magic. While a badge is attached to the cover of your spellbook, the gold and time you must spend to copy a spell of that badge's school of magic into your spellbook is halved. This effect does not stack with other benefits to reduce gold and time spent copying spells. You can collect multiple of these plates and fit them onto the cover of your spellbook, allowing you to gain this benefit for multiple schools of magic at once. Only the original spellcaster who attached the badge can receive the benefits of the badge. No trading badges amongst spellcasters.

You can use an action to attach or remove a badge from a spellbook by expending a spell slot of a level equal to 1 plus the number of badges already on the book (a maximum of a 9th level spell slot).