If I'm correct, you need to have the threesome with Hellhound and the Wyvern. As well as progress through Vampire's storyline to where you get the organium from the volcano.
how to do this cave scene? in fact I remember a time when I managed to do a scene where she was in the secret room dressed as a maid (I don't know if this scene needs threesome sex in the cave)
To do the threesome, you must impregnate the Wyvern, find hellhound in the secret room wearing the maid outfit, then after having sex with her you can do the threesome
It requires that you impregnanted the wyvern Leneth, to get Hellhound's scene in maid uniform at your secret bedroom in the castle. The maid scene is not always available, as the trigger for it is a randomly generated number, which can be re-rolled by using the Central teleport stone.
