This is my favorite so far, great work.
It feels like its combining strengths of both the previous pictures - the glyph bearer facing a monster from the first, and the clash of different time periods from the second - without anything taking over. I agree that the composition of colors was a bit better in the second picture, the watchtower created a interesting tension that isn't present in this picture, but I fell it's minor and not anything I would have reflected over if you hadn't pointed it out.
I don't know if you read my comment in the previous concept art post, but this picture was pretty much spot on what I had hoped for