They've never really been associated with that though, and Kraken in WoW would definitely be Ozumat who got his ass kicked by Neptulon in Legion's beta though it was removed and replaced by another quest.
http://wow.zamimg.com/uploads/screen...mal/640266.jpg
Those are most definitely tendrils, I don't get how people see those as waves, zoom in and there's yet another pair of thicker ones that look exactly like the ones we've seen in N'zoth's Hearthstone art.
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I do disagree with you on the part where you say old gods operate through subtlety, only phase one is ever subtle. That's when they slowly take control of the armies (Mantid, Qiraji, Ulduar)
But then, when it reaches phase 2, it's full on war as we've seen. And we never get to see phase 1 because it usually happens before the player character arrives for gameplay purposes.
Though I do too think that Azshara will be the one attacking. She'll probably destroy Azeroth's coastal zones or remake them (imagine a green Westfall).
It's about time they do something with it, we know they want level scaling applied to the old worlds, this is the only chance they have as we're going to space after this.
If Azshara does something, it'll be on a grand scale, not just Stormwind and Orgrimmar. I personally hope she destroys those two cities so that we can finally feel a sense of loss.