The Hell Raiser event required the Mission Items Trident, Horns, and Fire. You have 11 days to complete the set and earn the Epic Ability. The event began on May 26th 2011 and ran until June 6th(?) 2011.
The Ancient chooses to divulge her ways of wickedness. Master the fires within your dark and twisted soul to transform into a Hell Raiser.
You must collect 30 of each item to complete the ability set.
Each ability has 3 levels of mastery. Mastery of all abilities earns the ability Hell Raiser.