Tip: Once you get to the point were if you send your hero imediatly it gets killed simply make the enemy hero to do the same! The enemy hero will only go out if you're close if it gets hit so use a skill to damage the enemy hero to bring him out and if you use the metiorite (or other fast skills) he arrives so quickly he bearly has any troops with him and is super easy to kill.
for those comments on the ending of the beggining and the end i think the beggining was just the story the prince told evryone thats why we dont get that ending