The Lost Cavern is a rather straightforward navigational path. As soon as the Slayer enters the Cavern, immediately ahead is a locked chest that can be lockpicked. Further in, there are a few small encampments of goblins of rather inconsequential level. On the map, the word KEY highlights the area of a goblin throne with the key sitting on the seat. This is the key that opens the door highlighted by a teal square. Within the door is a room very different to the surrounding cave, consisting of a throne and some animal skins, a pair of casks, living quarters and a desk surrounded by books.
Upon entering the final room, there are three chests. Immediately on the Slayer's left, are two chests in a corner. On the other side of the broken shelving, near the bed, is another chest. There is one final chest in this room but it cannot be acquired until reading the book on the desk in the far corner, marked by the green letter B on the map. After reading the book, walk to the throne and stand there for a few seconds. The throne should glow and then a chest should appear on the seat, containing the Amulet of Slantwig.