From publisher blurb:
The highly anticipated expansion for Mythras Classic Fantasy!
Classic Fantasy has become a popular branch of the Mythras family, blending the Mythras rules with traditional dungeoneering adventure mechanics. The Classic Fantasy core book presented everything needed for Ranks 1 to 3. This volume, long in the making, expands Classic Fantasy to Ranks 4 and 5, with updates and expansions to certain rules, but more importantly providing the additional magic, monsters and treasure for higher Rank characters and adventures.
Unearthed Companion is compatible with Classic Fantasy core, and Classic Fantasy Imperative. It is not, however, a standalone book: possession of Classic Fantasy, Mythras, and/or Classic Fantasy Imperative is necessary to make full use of its content.