Our main tank (templar) wasn't here so we decided to try a 5 man run for fun. I'm normally not the main tank and thus did some mistakes which I highlighted so you don't have to repeat them.
My gear: GBG Pole +10 with SW fuse / Tac Dagger +10 / Tahabata Sword +10 / Full 50e / PvP Accs
Check what buffs you're using and only use the most important ones. It's very easy to overbuff stuff.
Use the default graphic option! The other one will cause client crashes.
Correction for what I wrote starting 10:40: We tested a different tactic in the run we did after and you can mostly avoid the stated issue if the tank doesn't run into the middle / onto the boss but instead runs to the side as he's doing in ...