The abundant number of players had clogged up the surroundings of the boss. Players without Flying Mounts were not even able to move freely. They could not even dodge the attacks of the boss. They could only witness themselves getting sucked into the vortexes, and their HP bars getting reduced at an insanely fast pace. Right after they get out of the vortexes, they would have lost over 99% HP!
The players were from different Regions after all. So when some of them are using Skills such as {Tornado Cleave}, they would accidentally wound the players from different Regions with their attacks as well. As many of them had lost quite a number of HP during the boss battle, they would just die on the spot right after they receive the attacks from the {Dark Vortex}.