I have successfully painted my entire collapsed Mordheim black! I couldn’t use spray paint because most of it is built with styrofoam, so I grabbed my largest brush, and watered down a lot of black paint, and got started. Here’s some pictures of my freshly painted black undercoat:
And here is a picture of it now that it has dried. (I’ve also spent about an hour doing touch ups and getting black paint deep into the crevices.
For this Mordheim building, I am planning on letting a lot of the black paint show through on the final product, so I definitely had to make sure every millimeter of this piece of terrain was base painted.