Just train Lulu up unti lshe learns the movie, it might help you defeat the monster, see this game you can't rush threw it you have to level up as much as you can, because after this boss you have to fight another one that has mines, and then you have to fight Yunalesca which she has three forms to kill, so if I were you level up some, it won't take long. then fight him.
because if your having a hard time beating a boss, that means that your underlevel.