Speak to Drinal's Steward near the second Tourbillion in Fearcreep at -2400, 201, 734 .
Speak to Gulthga back at the amygalain camp.
Kill Gulthga.
Enter the Throne of Fear: The Fear Gate. Be aware that as you enter the Fear Gate chamber, you'll encounter The Axiom of Fear. It's a 96 ^^ spirit, and not hard to kill per se, but be ready for some very...weird...happenings during the fight.