One of the books you need in order to play AD&D 2nd edition, together with the player's handbook and the dungeon master's guide. This book is a great alternative to the monstrous compendiums (they come in binders) which are being sold in high prices! Inside it you will find details and stats of over 250 monsters-creatures. This book combines the AD&D monstrous compendiums vol. 1 and 2, as well as some new creatures. Pick this up if you find it in a good price and if you intend to play 2nd edition AD&D.