Developing a Knight hero from the Haven faction.

I would appreciate it if someone could advise me on how to level up and play as a Warrior hero from the Order faction against a Necromancer mage hero, preferably focusing on a blood path build. Especially against that cheesy tactic with Sacrifice targeting Spiders, which is discussed in this thread: /topic/8577/. Even though my hero is stronger and has a larger army, all the damage seems to disappear somehow. How should I conduct battles, and what should I pay attention to during combat? There's so much written about Necromancers. But here, the topic is completely empty.