I also like the alternative creatures system in Heroes 4, but in Heroes 5, it's mechanically better implemented. For example, we have a defensive unit – the Archangel – and an offensive unit – the Seraph. What can be added to alternative creatures? Unfortunately, the number of abilities in the game is limited, so it's unlikely that we can create something truly unique. And honestly, I don't really want to see another titan with wings or a guy with a big sword like in Heroes 2, performing the same role as the Seraph. Therefore, I'm in favor of having one special unit for each faction that would reveal the faction from some unexpected angle.