Thanks for the report! The crown upgrades for both the skull and tooth should work again with the new hotfix 5.
Thank you!
Also: I don't know if it's intended or not, but now wizards are invulnerable to high spiked walls (they can't get through them, but they don't take damage anymore).
I have a suggestion for the "one FPS problem" that crash the game all the time for me in the late stages, or make it completely unplayable (kudos to the guy that can play with the 0,3 FPS :)). What about simply, instead of multiplying the number of ennemies to infinity, adding HP to them after the 30th wave? That way you can still get a nice challenge, without tanking your FPS.