Would it be possible to give the area a little bit of a makeover? It feels rather empty and disconnected from whats around it. With the lack of a good frozen interior tileset, the options seem a bit limited. But the frozen/snow floor placeable might help to make the keep look more fitting to the area, with some more ice stalagmite type things positioned about it would help feel as if you were actually stepping foot into a icy layer/keep.
