This is just in. It appears that the December edition of White Dwarf will have some exclusive cards in it for several of their games, including 40k and Shadespire.
While the source on this is beyond exceptional, we don't know much else yet.....
via sources on Faeit 212
December's White Dwarf will be a fun one. It will include exclusive cards for 40k, the Age of Sigmar, and Shadespire.
The cards have Exclusive Rules for each game.