Guys, how much money you need to invest in a project in order to get the 100th level of the castle?
I read in the telegram group that some people reached it without spending a penny.
You can invest about 200 imps and go fight other players (I advise you to do this if you have good artifacts).
If you are lucky, then 200 imps in a couple of hours can be turned into 600-800, but, again, if luck is your trump card.
I got so lucky one time, gained about 500-600 starting with 100.