From publisher blurb:
Learn the mysteries and power of the arcane tradition with Secrets of the Arcane! This tome presents new options for familiars, witches, wizards, and any arcane user for remasterd Pathfinder Second Edition character. For familiars, you will find new abilities such as Magical Resonance and Only Part Machine with a new specific familiar Crystallized Magic Shard. Witches can have new patrons: Hoarder of Frightening Scales and Twister of Spoken Wishes. Wizards can attend several new arcane schools with a variety of themes such as Banishment, Life, and Phantasm! Wizards can also choose new Arcane Thesis's such as Alchemical Magic, Battle Caster, and Hat Thesis. With 23 new arcane spells, you can specialize your arcane caster any way you want!