Tips on tactics and development in Heroes.

In the third game, there was a simple but very good development scheme, even though it wasn't explicitly stated! In the fifth game, after researching one skill, another will appear! But if you don't upgrade it... another one will become available! In my opinion, it's very difficult without a skill tree. Poor people who don't have internet. They will never find out (or if they do, it will be in 2 years) how to upgrade a hero and how the elemental chains work for the Dungeon faction!