The Visitor Event Guide/Discussion.

so probably: my damage sucks and i need to level like 5 more times or find someone willing to give me decent HB.

I haven't read the entire thread, but:
I spent about half an hour attempting to solo the 60+ boss today since my partner res died, and I learned a few things. I think the regular, multiple lightning strike attacks are % based, so hb wouldn't help if you're being mercilessly hit while frozen. When I was first attempting, I found that I could take two hits, and the third would kill me, but only by 200 hp. Once I changed from my quest specialist medal to my 4th job one to gain it's hp which should have put me over that threshold, I instead started taking about 200 more dmg per attack.

I've also noticed that all of the "regular" attacks have pitiful vertical range. You can still be blocked and bombed, but as a ranged, I start just below the first purple step to avoid regular damage for a short while if I get sealed. Probably already been stated, but the explosions go off when he does the "gears" animation if you are not sealed at that moment and are within range. Odd exceptions to this, such as standing still just outside the range, but it also seems that if the animation has just completed and you go into the range, it will kill you as well. I can't say too much definitively, but movement is key to going boom. That still doesn't help in the "what the hell is helping" issue though.

Kinda doubt anything I've said is new, but never hurts to share personal experiences if it could help others take down the 120.