Hey guys, justin here.
Today when i was leveling my lock, stumbled apon a brilliant grind/leveling system for aroun 65-70 warlocks! In nagrand there is a spot called Forge Camp: Hate, which hosts elite demons. With a warlock you can enslave these elites and kill other elites with them! i grinded from 66- 68 with this quite fast until i got bored.
ENJOY!