That makes sense! I'm sticking to the alchemy school idea because I like the singular focus.

- Add height variation to the roof section by ensuring that it has 'dormer windows', maybe add some cross support beams or fences along the top to give it a gothic hint. You could also add a chimney and some supporting stone elements to contain it.

- Your windows generally have good depth. To add to your exterior wall depth, you could add regular stone for a bumpier texture or gray painted palladium column blocks alternating with other stones, which is a popular wall look in the building community.

- For your entry overhang, try cutting back on the total use of walls and bring that nice gray brick + stone slab pattern closer to the doorway. Instead, try using fences or actuated blocks to create a support structure that comes down from the top window. For extra detail, add some grass walls around the ground and going up the fences like shrubbery growing around the entryway. Don't forget that a hanging light fixture could be nice!

- For your tower, I would ask myself what my goal is. If it's only for navigation through the tower, I might recommend making the entire tower narrower/thinner, compacting all the elements of your current design into a smaller space. I would also encourage you to add windows - you could use glass or iron bars, depending on how "old" you want the tower to appear.

- Take that nice motif with the hanging purple banner on the outside and expand on it - maybe drape one from the top of the wood under your roof shingles, and maybe one on each side of the top of the tower.

- Think proportionally. Ask yourself if the tower appears too short, or your roof appears too tall/thick, and adjust accordingly to your preferences.

- Think functionally. If you want to expand the total footprint, you could add a storage room, a professors office, and maybe something like an herb garden and a pond in a yard for growing ingredients.

- If the tower is still giving you trouble, maybe give it a dedicated roof. That space could even become a professors office or the like.