Against orcs, darkness is most effective, primarily through mass slow, dispel, and weaken, which will turn any army into useless fodder. And the subordinate cyclops are a real challenge... The unholy word is excellent for reducing rage points. And by the way, necromancers shouldn't prolong the game (not against anyone in particular). Gather archers, build a guild, and go ahead; by weeks 3-4, it's the right time for a necromancer to attack. You can easily gather 500-700 skeletons, and they can handle Black Dragons quite well.