Mystery of the Nightmare Venom is the second adventure in the Nightmare Venom campaign for the prehistoric D&D Planegea campaign setting. It is designed for four to five 2nd-level characters using the D&D 2014 ruleset. In the first campaign adventure, Venom Attack!, the PCs encountered an envenomed spider-raptor sent by the Spiderfolk Queen to attack Edgegather, while a minion of a green hag sought to collect a sample of the venom. In Mystery of the Nightmare Venom, the PCs begin to investigate this strange magical poison at the behest of the Venom Guard: A vengeful green hag seeks to corrupt the inhabitants of Edgegather. Can the PCs stop her before her poison brings the settlement to its knees? The goblins of the Unfalls may have useful information but the PCs must first retrieve a lost relic from the spiderfolk of the Venom Abyss before they can ask their questions. The PCs investigate a vast and ancient temple beneath Edgegather where the mysterious Veiled Goddess can point them towards the Oracle of Seerfall. Mystery of the Nightmare Venom contains five new monsters (the envenomed chattercrest, the envenomed Venom Guard, the cauldronborn, the Glassback spiderfolk, and the faithful remnant) and two new magic items, the bloodtallow candle and the obsidian centipede.

Venom Attack! is a short introductory adventure for 1st level characters using the D&D 2014 ruleset, set in the settlement of Edgegather in the prehistoric D&D Planegea setting. It is the first adventure in the Nightmare Venom campaign. An envenomed spider-raptor sent by the Spiderfolk Queen attacks a group of Venom Guards in the marketplace of Edgegather. The PCs witness the attack and can help to defeat the creature before it spreads the venom further within the settlement. A green hag lives secretly within the boundaries of Edgegather. One of her spies witnesses the attack of the spider-raptor and attempts to gather the venom for the hag, who also plots the downfall of the Venom Guard for her own reasons. The PCs can spot the spy trying to gather a sample of the venom and question him to discover a secondary threat to the people of Edgegather. Venom Attack! contains a new monster template, Envenomed, a new monster, the envenomed spider-raptor, and a new magic item, the fetish of the pseudodragon.