i played around with in ptr. it seems really nice pve content. only the patch notes mention a shop where you can buy the heroes with the currency you get only there doesnt seem to be a shop anywhere to spend it.
Maybe a future content? But I saw Avalon there and you could buy him for 300 things, the question is if he is only for use on the Void or outside too. They also talked about Nora, Gan and Wraxius being obtainable for free, so, they could be on the 20+ zone