I got a nice surprise in the mail the other day, an advanced copy of the next Catacombs expansion, Wyverns of Wylemuir.  I helped Elzra Games proofread the manual and components and as a fantastic thank you gesture, they sent me my copy early. This is a full expansion similar to Cavern of Soloth so you need the base game to play it.  I believe there are a couple of other copies floating around as it was available to purchase at Dice Tower Con.