Took me 12 hours to devise a plan to beat this quest
There are so many obstacles in this quest which make it so hard for QSH to solo such as the buff removal of Tristan , Gareth NP (which has ignore invincibility) and the stupid formation
I think that this one is difficult to solo with QSH just like OOKU CQ , mainly because of that cursed Tristan which remove your buffs every turn
The best way to beat this quest is with AOE archer like Gilgamesh (Gil can actually solo this easiliy) , Ishtar or Tesla
Another good AOE non-archer options are Space Ishtar , Arjuna Alter and Summer Musashi (next year when Castoria will come)