5.1 Brings Green Fire!..
Check out this concise little article over at Wowhead about the new epic warlock-only quest line coming in the next patch. It will provide us with the Codex of Xerrath which according to Wowhead at once said "transforms the color of your Warlock fire spells into a rainbow. Also, summons Unicorns."
"Then we return... one year from now and take the results of our expeditions back to our own sects. More powerful than we would have been alone."