the mark of the betrayer has a completely different background than you know...
found this on an ancient thread.
"There exists an ancient order originating in the Ionian Isles dedicated to the preservation of balance. Order, chaos, light, darkness -- all things must exist in perfect harmony for such is the way of the universe. This order is known as the Kinkou and it employs a triumvirate of shadow warriors to uphold its causes in the world. Cheng was one of these shadow warriors, entrusted with the sacred duty of Pruning the Tree - eliminating those who threaten the equilibrium of Valoran. Until one day Cheng betrayed the order. Cheng descended into darkness too deep and too often to return, her acceptance of chaos twisted her definition of order."
I feel strongly that the black mist has something to do with what we see here, but surely, the mark of the betrayer has something to do with betrayal, as opposed to simply shadow isles black magic, and what-not. and honestly, who knows anything. all I've found are rumors of rumors, but I believe I'm on the right track...
too many unanswered questions...
EDIT: added more of the quote, and if you didn't know, triumvirate means group of 3.