Creature stack experience like in Wake of Gods

This might be more appropriate as a mod or an optional feature but I really loved Wake of God's unit stack experience feature. Better stats, more hit points, and special skills and abilities that activate as your creatures gain experience.

What about the aesthetic impression then? In Heroes 2, there was a clear distinction between "sentient" creatures (usually upgradeable, including Dragons) and "non-sentient" creatures which are simply giant animals or beasts cooperating with factions on an unspecified basis. By letting the Boars progress in a similar way as the Paladins or Magi do, you are killing this aspect of atmosphere, which is pretty important in Heroes 2. In Heroes 3 this design aspect was different since all creatures were upgradeable, and thus were perceived differently by the players. Having the "veteran status" Boars versus "totally green" Black Dragons will surely cause a lot of discomfort.

It breaks the aesthetic in a simpler way. HoMM II is very much about simplicity. Few mechanics, few abilities, done well.

Like many things, this feature will be possible to support by Lua scripting, and we will gladly offer guidance to anyone who intends to do so. The Ironfist team will not be adding this to the game, however.