Hey! thanks to Die Wälkire i've come to this, and i found it AMAZING!!!
But i may suggest something a bit different (due to my late arriving to this debate):
Yes, we could purchase some upgrade in the citadel, but instead of surrounding randomly the fortress, could it unlock another option for the defensive plots?
What i mean is that instead of only getting warg sentry or sentry tower we could add a gondorian-like tiny tower-building that summons this non controllable guys. & maybe by selecting this building their armor-weapons could be upgraded:
Normal citadel (but already purchased the upgraded):
Orthanc Guard lvl 1: summon four lesser numénorean soldiers to defend the base. Wooden spear equiped. Pasive ability. (the idea is -as read in this tread- to summon soldiers more dunland like than gondorian like).
Once we upgrade to excavations:
Orthanc Guard lvl 2: summon four lesser numénorean great armored to defend the base. Gondorian armor equiped. Pasive ability. (the more the citadel improves the more the soldiers get better)
& when we get the wizard's tower:
Orthanc Guard lvl 3: Summon four lesser numénorean heavy armored to defend the base. Tower guards equiped but with the white hand instead of the white tree.
*They will act as the warg sentry: they will attack when enemy gets too much close to the base.
*They will not be cumulative, every stage will kill automatically the previous ones and summon the new ones.
*They wont be selectable.
*They wil look pretty nice
Hope it is not too late, but rememember what Gandy says: a busy man arrives precisely when he means to ^^