It has been heavily hinted at in the past that she is essentially an Old God, or at least a fragment of one. Considering the blade containing her was rediscovered under Tirisfal, which has been teased to have had an Old God slumbering beneath it, it would make sense. If she is one, then she’s not your average run of the mill Old God. She’s probably a front for a bigger threat, however. My guess is that she’s a fragment of a still unknown Old God or perhaps she’s actually a Void Lord given form.