The Four Horsemen/Zaishen Quest

Summary

 * Kill the four horsemen; Marduk Dhuum, Thul Za Dhuum , Ghozer Dhuum , Kazhad Dhuum in the Underworld.
 * *BONUS* Kill the four horsemen in Hard Mode.

Dialogue
Kill the four horsemen; Marduk Dhuum, Thulza Dhuum , Gozer Dhuum , Kazhad Dhuum in the Underworld.
 * Accept: "I can do that!"
 * Reject: "No, I'm way too busy today."