You will have no renown (Everyone's forgotten you during the centuries you were in your tomb, and those who haven't don't believe you are the long-dead King.
If you start with high leadership and training, you can immediately build a large, powerful army.
Cover the world in darkness and take back your kingdom! with all of your powers but no resources (or a chest of gold if that's your thing). Optionally first convert all gold into diamonds so they don't get saved. Spend any qualis gems you have on elixirs to boost your character, save your character via the character/stats menu. This is the most fun I had in PoP except for the first ever playthrough when everything was new and cool.