The Living Tome

The Living Tome is an animate spell book with legs and a tail. If the tome befriends a spellcaster he can use it to cast spells. This includes spellcasters like Warlocks, Sorcerers etc. who normally cannot cast spells from spell books. 

The tome contains one random spell of each level the spellcaster has access to but does not already know. One of the tome's inventory of spells refreshes whenever the owner levels. 

The tome can camouflage itself by assuming the appearance and dimensions of any book it has come into contact with.