I remembered this thread today since i finally got to the end of the tower. It only took 170 hours (almost half of it is pure grinding). The game changed a lot since i've stopped playing and the broken shrooms got much rarer, so i've stocked them for the end and the end boss was easy with them.
After that, it opened more floors that raise the challenge a lot, but i'm not onterested anymore. I wanted to get there and i got it. I'm pretty happy with it. Without spending a single dime on it also.