Future expansions.

Very interesting. Although, won't this create an imbalance towards one of the creature versions? I'm not an expert on Heroes of Might and Magic V, but it also has alternative upgrades, and as a rule, I always choose only one – the most extreme one. The other units end up being unused. Hmm... however, if you have heroes with different reputations, you can vary and tailor armies for different combat tasks – or as a counter to the opponent's development. Interesting. For example, in StarCraft, if one player goes for Mutalisks, the other, as a counter, builds Marines or Phoenixes, etc. But that would require a lot of balancing...