I have been playing with Mordor, but I seem to not understand fully how they are supposed to be used. I can't build attack trolls from the troll cage and I can't research weapons/armor upgrades like flaming arrows. Is this intended? I build the shadowy Sauron and use his abilities to focus his attention on various buildings to enhance them, but when I did this to the siege works and troll cage no new options became available. Please let me know what gross oversight I have made here. Thank you.