Rexsar
Auto-translated
I don't know how to kill Hangwula.
He increased his army by 25% during the week it took him to reach the castle, and in battle, he constantly uses Rune Recall, which gives him infinite mana. Otherwise, he uses Earth Shock, Meteor Shower, and Fireball. He doesn't seem to use Darkness, only Chaos. This explains his magic power and infinite mana.