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I believe that a hero should be chosen based on their unique ability, which should be as versatile as possible and have a broader impact on the army. Heroes with individual traits that only apply to specific types of combatants (e.g., +1 to archers, +2 to wyvern armor, etc.) lose their "unique ability" in any immediate situation (blindness, mind control, berserk, or simply when your favorite centaurs or assassins are defeated), and that's IT! The hero becomes just another ordinary unit! Of course, this doesn't include their overall level-up. By "broad ability," I mean, for example, Krag's first strike, which can push back overly fast knights, or the ability to increase the attack of the entire army for each enemy killed (I don't remember the name of the hero). In general, all heroes (including those from other factions) whose abilities are more popular and not limited to a specific "stack" (if I understand the local slang correctly:smile09:) are better. IMHO.