2. What happens when either of those Divines decides he/she no longer wishes to be a MINION?
a) You enter your dungeon only for inside minion to refuse to res you - He/She then takes your place!
b) You need to go out and terrorize some villagers - Whoops, Outside Minion's decided to go elsewhere for work!
Not only are you now dead BUT your Minions are all stuck Inside your impregnable Dungeon!
3. Adventurers come along while you're inside said impregnable dungeon and figure out that all they need to do is Kill Outside Minion and you and your army can rot inside!
Oh and if you can Teleport in/out then PCs can too!