From publisher blurb:
Eldritch Akasha:Whispers of the Old Ones brings even more mythos-themed flavor and abilities to the Akashic Magic substem for PF1e! Wield the powers of the old ones to utilize eerie and esoteric effects to modify your own form and inflict strange conditions upon your foe, form cults in their name, or uncover ancient and forbidden powers!
Contained within this books are new:
Promethean Obessions: Two new obsessions for the promethean; the broodsire and the hivemind!
New archetypes and class features for the Guru, Promethean, Soulforgem, Volur, and Zodiac! Follow the teachings of an old one as a Herald of the Old Gods volur, unearth ancient and forbidden knowledge as a Seeker of the Forbidden promethean, or wield the power of ancient and powerful lost constellations!
Veils Sets: A new veil set, the Whispers of the Old Ones, containing five new veils that utilize their powers!
New Veils: Two new veils themed after notable members of the mythos, the fearsome mi-go and the Elder Sign itself!
Storm Veils: A new storm veil that inspires madness in all that lay eyes upon it, The End of All Things.
Feats: Five new feats! Improve your abilities as a broodsire or hivemind, or create your own cult of followers dedicated to the old god you worship!