Exactly what is Joko? His origins, where did he get his power? He's definitely unique. Not even Ziatan's Liches demonstrated Joko's ability to just pop back from the dead "like a demented jack-in-the-box," as Taimi put it. Yet, he seems to have been just a normal human at one time, as he does look just like any of his Awakened, and there's an ancient inscription in Southern Elona that you can read in Guild Wars 1 which mentions Joko and just calls him a "raider." It seems like at one point he discovered some great and very unique power.
Maybe given his choice of putting his capitol so near the mouth of torment is a clue? Maybe he somehow absorbed magic from the realm of torment? Maybe he somehow discovered the existence of Ziatan long before any human, and found a way to steal some part of it's power? But these explanations don't really fit, because neither Ziatan nor Abaddon ever demonstrated Joko's ability to resurrect themselves.
I just wish A-net would give us some clue.