Yeah, as we got already castle which can be healed and it self-heals and is tougher. So adding third protection to it (and occupants) would be overdoing it (or fourth if count cloak of mastery). So weather control could be cool (allowing create whatever weather you want outside the castle). Or there is always plentifully food/drinks around in all spaces which function as heroes feast when receive such nourishment. Or from soul drinker side the castle is able fire soul powered lasers upon any enemies who approach the site.