Demong Cults & Secret Societies has thirteen enemy cults and societies to run against your players. The OGL content includes the archetypes, feats, magic items, monsters, oaths, poisons, and spells. As with Tome of Beasts, there's a large number of NPCs which are not included since it's not clear that the generic NPCs are "monsters" for OGL purposes.
OGL Content:
Bituminous Orb - (item)
Blood Hound - (monster)
Blood Strike - (spell)
Bloodwhisper Cauldron - (item)
Bone Whip - (item)
Broth of Needful Fortitude - (item)
Carriage of Whispers - (item)
Chiroptus Demon - (monster)
Clockwork Seige Crab - (item)
Conjure Manabane Swarm - (spell)
Consuming Rod - (item)
Curse of Formlessness - (spell)
Dark Dream (Inhaled) - (poison)
Delay Passing - (spell)
Demon, Echo - (monster)
Diversion Expert - (monster)
Doom of Ancient Decrepitude - (spell)
Ebon Shards - (item)
Emerald Tablets - (item)
Exsanguinating Blade - (item)
Eyes of the Outer Dark - (item)
Feed the Worms - (spell)
Flame Eater Swarm - (monster)
Flame-Scourged Scion - (monster)
Fungal Flyer - (item)
Ghoulsteed - (monster)
Golem, Altar Flame - (monster)
Golem, Smaragdine - Lesser - (monster)
Incantation of Lies Made Truth - (spell)
Infernal Oath (Antipaladin) - (oath)
Ioun Stone, Emerald Shard - (item)
Jerky of Desperate Strength - (item)
Maddening Blindless Poison (Contact or Injury) - (poison)
Mantle of the Mother - (item)
Mayhem Mask - (item)
Monkey’s Paw of Fortune - (item)
Morphic Flux - (spell)
Oath of the Crawling Beyond (Antipaladin) - (oath)
Paincaster - (feat)
Pâté of Complacent Purpose - (item)
Primal Doom - (item)
Roachling Lieutenant - (monster)
Sanguine Spear - (spell)
Scattered Images - (spell)
Scorch Bomb - (item)
Scourge of Devotion - (item)
Selfish Wish - (spell)
Selket’s Bracer - (item)
Shadow Spawn - (spell)
Shadowmaker Poison (Injury) - (poison)
Skittering Skiff - (item)
Staff of the Bat Demon - (item)
Stigmata of the Red Goddess - (spell)
Tengu Bravo - (monster)
The Black Goat Wizard's Folio - (item)
The Black God’s Blessing - (spell)
The Father’s Staff - (item)
Tome of Bound Flesh - (item)
Umbral Lantern - (item)
White Ape Hide - (item)
Wield Soul - (spell)
Winged Spies - (spell)
Zombie, Blood - Lesser - (monster)