Spell of Mastery Progress
Importing that tower into the game proved a bit more involved, since I also want to draw interior properly. And that requires special cases for floor, interior uncovered and fully covered versions.

It also exposed more a few more bugs and one segfault in the rendering code.

Obviously that tower is also multi-layer and the piece on screen is just the first layer out of 4.

Guess now I've made the most complicated isometric engine ever conceived.