There is no section for new wall types (!) I think there needs to be a new type of wall bought using dark elixir. It would be limited to two wall pieces at TH8, 3 at TH9, 4 at TH10. It looks different to the owner, but looks just like wall type adjacent to it for attackers. When someone attacks it, either with a wall breaker, or with another troop, out pops a troll (lol!) - this troll would have the same stats as a valkyrie, and would defend like a valkyrie does.
