You probably missing something then, because first 6 floors are pretty easy to beat even if your setup is far from being any strong. You may experience problems in magma core on many build that found not enough power on the way, but also it isn't that hard to beat magma core as soon as you get some experience with the game, items and combinations. I'd say I was beating 9 floors on about 80% of my runs, then usually dying to magma core+ on the most of them:)
EDIT: Admittedly, game received an update recently and people say it became harder for the main part. Have to try it myself yet, as I was a bit busy lately:)