How do I complete the final mission playing as Roland?

Let's consider the main prerequisites. 1. There is a magic skill of 10. 2. There are many companion castles, including a castle with dragons. 3. To win, we don't need to capture all the castles and defeat all the enemies, but simply defeat Archibald. Based on this, we can try the following game plan: a rapid raid to the center to capture the main dragon castles; learn magic there and send several heroes with powerful magic to attack Archibald, while Roland finishes him off with dragons.