World's Largest Dungeon
The handbook is a actually a series of loose pages discovered by the Moon Elf Menelri that reacted to her touch and revealed the Empyrean Eye to the elderly Rohmer Cabot outside the cave entrance to the mysterious prison.
Cabot has used what little ‘free’ time he’s can to craft a suitable cover for these pages as he translates and learns to wield the magic hidden within the pages, creating a sort of spell book.
So far he’s compiled the following spells -
Protection from good and evil
Melf’s acid arrow