i see a lot of people at this fight have no idea what they are doing or using a strategy that is in no way effective for the fight. now i am attaching a picture i hope i do it right as this first time i have tried to do this on this site. in it shows the best attack plan for next to last boss in coh2.
a basic over view is you split group into 8 zones based on the pillar, 4 player zones, 4 safe zones between player zones. each player will pick a north/south pillar, one on each side of the entrances into the bosses area. thier zone will be from that pillar to the 3rd pillar to the west/east. the space between the east/west/north/south pillars is the safe zones. safe zones are buffer zones to ensure not overlap of bubbles. also they provide a safe zone for players to roll into if they get the lion share of the randomy placed bubbles. but you should always aim for the edge of the circles as close to your zone as possible. this is how experts at this fight can do fight and never die (including if another has to use the same safe zone.
https://facebook.com/photo.php?fbid=1259305510775021&set=a.1242320222473550.1073741827.100000867530305&type=3&size=766%2C717
v160 spellsword (nightblade)
v160 restoration archmage (Templar)
v160 battlemage (sorcerer)
v160 restoration archmage (Templar)
v160 warrior (DragonKnight)
v160 assassin (nightblade)
v160 swordsman (sorcerer)
v160 spellsword (nightblade)