One might say that the ultimate power granted by Ghor would be if a warlock or necromancer is turned into a lich. The liches undead state grants him or her immortality so long as their phylactery remains untouched and unlike the undead created by necromancers they are fully sentient beings still. There are even records of liches that were so powerful they actually had several phylacteries that all needed to be destroyed before the lich itself would become mortal again and could be killed. Liches are one of the most powerful on Ghor’s creations.