The final confrontation with Dagoth Ur is less about direct combat and more about a puzzle. He is initially invulnerable due to his connection to the Heart of Lorkhan. You must use Kagrenac's tools (Sunder and Keening) on the Heart to sever this connection. Dagoth Ur will attack you relentlessly, often teleporting and using powerful spells. Focus on reaching the Heart and using the tools, rather than trying to defeat him conventionally. Bring plenty of healing and Magicka potions.
