Witcher 3 Folan Kaer Morhen Geralt first encounters folan in a large cauldron about to be made into warrior stew by two ice trolls in a cave north of the abandoned village on undvik

In battlements of kaer morhen locate an open iron barred arch which leads you to a quarter where you will find some old papers written by berengar in a chest one of these here use your witcher sense to locate a registry tome to read and rusting experiment tables and your quest will complete here