Collector's Arcana: The Companion Rules are Set 3 in the Dungeons & Dragons rules series. It consists
of Book One: A 32 page Players Companion and Book 2: A 64 page Dungeon Master's Companion.
Description (From the back cover)
"THIS IS SET#3. TO BE ABLE TO PLAY THE COMPANION SET, YOU SHOULD ALREADY HAVE PLAYED BOTH, D&D BASIC SET AND D&D EXPERT SET.
FOR CHARACTER LEVELS 15-25
Players Companion — Featuring rules for unarmed combat, strongholds, and new weapons and armor.
Plus more advanced rules and spells for your characters.
Dungeon Masters Companion — New rules for ruling realms and the clash of kingdoms.
New treasures and monsters. Plus new adventures for your high-level characters."