Well, I mean, I posted it on the server just to be like "yo, look what I found". And eventually that led to people discussing what this was supposed to be, since, you know, there's no way they'd just casually reveal the Doctor's real name like that, right?
And then that quickly led to people posting screenshots from the Doctor Who Wikia. Because of course this phrase has been documented somewhere on the Doctor Who Wikia. XD
Apparently the phrase has been used a few different times in Doctor Who, particularly in the more obscure, semi-canon stuff like the novels and comic books. And all the Wikia had to say was that it's probably some sort of scary title like "destroyer of worlds" or "bringer of darkness", and that the Daleks started calling him that after he destroyed Skaro.
...Except, the Doctor destroying Skaro is a thing that happens in the book that I found that phrase in. And he doesn't destroy Skaro until much later in the book, after the phrase is first used.
I would say "wibbly-wobbly timey whimey", but, even from the perspective of the Dalek that narrated that part, it's still true that Skaro hadn't been destroyed yet.
So
¯\_(ツ)_/¯
