After 11h of grinding like noob I'm still stuck and can't defeat the Boss Luna. I'm at lvl 46 with the team and lvl is taking long as hell. Any guidane? I thouht about cheating bc im already that frustrated but it's not so easy done like in RPG make. Thanks

Using the shark's blood or the acid the clan occasionally gives you when you defeat them is the easiest option I can recommend.

Another option would be to obtain a replica of the Luna katana, but that's not possible until Luna is defeated.