To defeat the Witch King at the Pelennor Fields, make sure that you have Hadhod's Second Age Dwarven Mithril Piercing Axe and the Dwarven Mithril Helm. When you face the Witch King, use these attacks: Berethor's Stunning Strike and Ectehlion Wrath, Hadhod's Mountain Rage, and Eaoden's Enraging Blow and Rohirrim Rage. The Witch King has 200,562 HP and 59,098 AP.