From the official AoS FB page:
Ready your axes and prepare for a gladiatorial arena bloodbath the likes of which the Mortal Realms have never seen.
We're delighted to announce that this September will see the release of a brand new boxed game set in the Age of Sigmar. In Gorechosen, Champions of the Blood God battle each other for glory under the eyes of Khorne himself.
To the victor will go the favour of the Blood God. To the the losers, well… that Skull Throne always needs more offerings.
This box won't be available to order for a few months yet, but seeing as how it will be providing you with four Khorne Bloodbound heroes, and with the Season of War just a few weeks away, maybe it's time to start that Bloodbound army and get a head start (get it?) on collecting skulls for the Skull Throne..