Rary's mnemonic enhancer

Rary's mnemonic enhancer was a transmutation spell that was only usable by wizards and clerics commanding the spell domain.

To Zakharan mages, always reluctant to acknowledge ajami names and accomplishments, the spell was known simply as mnemonic enhancer, and counted among the spells of the universal province.

It allowed one to prepare extra spells or retain one that was just cast, and was presumably developed by Rary.