Awakening Stones (Type Varies)

Awakening Stones can be found in magically saturated areas or gained from a looting ability. In a place where wizards, bards, and any other class is unable to find new spells, Awakening Stones allow them to gain new or change old spells. They can also be sold. For example, if you find a Water Awakening Stone then you can use it to "Awaken" a spell that has something to do with water. 

DM Notes: Since there are too many for myself to create alone, just edit the item to create whatever essence you want to give to your player. You can also make a rarity system if needed, like higher rarity stones allow for higher rarity spells etc.