From the publisher's website:

Smash Up: The Obligatory Cthulhu Set features crazy Cthulhu cultists, fishy Innsmouth locals, horrifying Elder Things, and good old Miskatonic University members (the Fightin’ Cephalopods). To be certain we got it right, this set also includes a new card type fittingly known as “Madness”, that each of these groups use to various effects. But remember that Madness brings you power but at a price (joking!). If you’re ready to embrace the creatures beyond the understanding of mortal men, then shuffle up these guys with your pirates, bear cavalry, and others for the most awesome fit of crazed insanity you’ve had in a long time! Cthulhu Cultists – Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn! Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn! Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn! Elder Things – From reaches beyond space and time come these incredible horrors, bent on… bent on… well we really don’t know, do we? Every time we learn a little bit, we go nuts. Perhaps its the madness they cause that gives them power after all… Innsmouth – Ah Innsmouth, idyllic little fishing village on the New England coast. Sample their excellent seafood. Become their excellent seafood! That’s right, you too can become a fish and live with Dagon below the depths. They may look like simple mutants, but in great numbers and with great power the residents of Innsmouth will welcome you into the fold. Or else. Miskatonic University – Go ‘Pods! Go ‘Pods! Welcome to your first days at Miskatonic University! We will shape you into a student of the sciences both natural and… otherwise. Certainly our courses seem intense, but there always has to be a small sacrifice for knowledge. “Ex Ignorantia Ad Sapientiam; E Luce Ad Tenebras.” Combine these groups into teams of two for various effects! Smash Up: The Obligatory Cthulhu Set also contains 8 new Base cards to compete over.