Board Thread:Questions and Answers/@comment-25270263-20140805232252/@comment-25234280-20140807153843

http://yasushi.me/ayabeta/tower.html You can use this link to configure the best team for you, as well as know how likely it is for you to beat the 75th floor with your team. It's not in English, but you can still easily find the daemons that you use in it.

If you have those three maxed along with the rat clan boss and Thomas at those levels then you should have a 90% chance of beating the 75th floor. SO the answer is, is that you don't really need to level them up anymore, but it will help a bit ^^