Board Thread:General Discussion/@comment-4962906-20151007080647/@comment-24674051-20151007173242

[MOD] Guys, be careful with the spoilers. Episode titles are spoilers until at least the publication of the press release, and this thread is currently in the general conversation. Given that we have Merlin in a tree, and anyone familiar with Arthurian legend knows about Nimue (or any number of other names she goes by, depending on the legend) and that she trapped him in a tree, I'm letting this one slide as the title alone does not give away anything that we would not expect at this point. Any more slips, and this thread gets moved to Spoilers.[END MOD]

As for Nimue being the first Dark One, Nice theory, but just to make sure everyone is aware, that is speculation. We don't know if Nimue will be a Dark One, or if she will even have any part in the Dark One Mythos. (I personally would be surprised if she didn't have some part).