The eldritch gods demand your sacrifice! Take your partners and head to the dark kobold shrine, deep underground, where you can desecrate the altar with your lust. Let the stones echo your moans, let the air stiffen around your sweaty bodies. Hail the dark ones!
The altar could be found deep in the fox burrows. Head into the forest until you reach the deep forest, from there go hole, go down, go north to the Library, pull the bookshelf lever, go kobold from the dark caverns, and finally head to the cursed room.