Balance in Heroes 5.

To Lord Vampire: It's foolish to think that you can constantly win with the same tactic. You might win once, but the next time, they'll use a counter-tactic, for example, 2 skills with +15% resistance + unicorns. The shock will only go through one out of four times, and if you consider your army and your opponent's, you're guaranteed to lose. Furthermore, no one prevents you from recruiting neutral heroes, like Imps. No one stops you from attacking with 3 level 5 heroes with the same lightning spell before the main hero attacks. You'll either have to spend mana to quickly kill them in 7 slots, or you'll lose gargoyles, etc. As they say, for every clever trick, there's a counter-trick.