I killed Captain Nebula after Organization XIII told me to, and when I went back to Hank Hill, he told me to speak to spongebob for the answer to the puzzle on the back of Chronos, wherein I found a merchant who sold me the Gjallarhorn, which was just a bonus. The merchant, who's name I never caught but who's T-shirt read "the first of the wise men", told me to go and defeat the Goliath Pinhead in the depths of the hellmouth. So I killed Pinhead, who WASN'T actually a Goliath (DAMMIT BUNGIE, FIX YOUR GAME), and when I emerged from the depths of hellmouth, Shrek told me to kill 500 guardians with void weapons and a kilo of heroin (not the drug. Shrek peeled 2.2 pounds of flesh off of a heroin) After that, Grundy and Bane told me to kill xylor the unwed, phogoth and guy Named tesla for it. Totally worth the hours it took.