I've seen Ermor stack as many as 1,700 troops on a single province and in most games he usually does not cast any domes for protection even for his capital.
The mass building of armies is good... yet the AI never launches these units into battle after building them. It's attacks are usually insignificant during late game.
That's not the only unusual tactic Ermor does... for some reason Ermor does not research blood magic ! During one game Ermor sky-rocketed on research which is EXTREMELY rare to see and then leveled off on the graph much sooner then myself when researching was finished.
During this game Ermor was bringing in 10 death gems a turn at this capital yet even with research maxed out he never casted Ghost_Riders. Thus one reason I don't use this spell against computer opponents.