the heroes in silver tower being release separately was also weird since only the Darkoath, Knight questor, Doomseeker, and Mistweaver (which doesn't belong to any army) are available to buy but the Warpriest and Shard are not available on the webstore.
the one in Blackstone have not been release separately (because they share the same Sprue) but also their expansion are all limited run (the Zoat, the traitor Commissar and Ogyrn, and the giant Spindle drone)