Names
I think Raven Queen has one weakness: it lacks traction. Using some old names, Norse, Celtic, Shakespearean, might have worked better, even as descriptive names.
Now if it had been: The Queen of Air and Darkness, or the Erl King, that would have pressed my "Mmm, legends" buttons. One of Odin's nicknames is"The Gallows God" that has a deathly feel, or even Faeruns "The Darkbringer" aka Moander.
Tiamat was good. Bahamut: meh. Too like Baphomet in sound. Marduk, another name for him, in ancient Faerun, was better. Again, traction, old and famous.