Need Help to Beat Boss

Can anybody make a short AR Code for a one-hit kill or give me some help on how to beat the final final boss because I used the all item code that came with my AR to get the super-rare Geos and used the best one which brings it down half and my Spectrobe's combo attacks aren't working, it is immune to it. So can you tell me a good combo, I basiclly got every spectrobe there is and just cant do it.

don't use a geo until it has the shield up or you can't defeat it.

ok so first hit it with a combo attack then hit it with the geo?

I recommend using some quick attacking spectrobes. then when you get the chance hit it with a combo. or a geo. BUt if you have a AR coder, use the all mineral gode, it works great