The Black Box expands Catacombs 3E with a new double-sided 3E compatible playmat featuring the Athenoch Mortuary on one side and the Notholag Dungeon on the other. It provides a full set of alternate monsters cards for the base Catacombs game plus every Catacombs 3E expansion published so far including: Cavern of Soloth, Resurrection, Wyverns of Wylemuir, and Keystones & Keeps. There is a new set of monsters for the Vermin family and the new Mushroom familiar for the heroes. In terms of rules, this expansion introduces the snowball ranged shot, group rush shot, move to rune "shot" and the transmogrify shot modifier. The box artwork is an homage to the cover of Catacombs First Edition, released over 10 years ago.