Burning Crusade-era warlocks were the best. No diminishing fear cooldowns so you could spam it and keep someone crowd-controlled as long as you had mana. One of the curses let the victim run around for 30 seconds before it killed them. Rogues and shadow priests also had similarly broken mechanics so you could really fuck with people, but a warlock glitching above a capital city and then griefing the streets below was uniquely strong.