I didn't quite understand this part. So, it kills the killer who hasn't killed anyone yet and dies along with him?

I forgot to remove this while editing. In an earlier version, the Adept's ability changed the abilities of other roles when used on something else. For example, the Ranger would learn the opposite status, the Mage wouldn't heal but would block, and so on. But in the end, I decided to remove this.

I would say that the Mafia is strong, but with so many maniacs...

That's the point. Almost all victories in games, starting with the first ones, were based on luck and randomness. That is, the more roles and features there are, the more interesting the setting, but the more the factor of randomness influences. But almost every one of our games suffers from this.
By the way, in this game, there would be strong restrictions on notes, you can understand why, due to the abilities.

A couple of maniacs – and that's the second Mafia, you could say. In essence, I could have simply introduced a second full-fledged Mafia, but I decided to do it this way. I've wanted to try something like this for a long time.