I don't know how much more detailed it needs to get, it's exactly how it's supposed to be done.
--At the start of the event, there will be 5 different bosses spawning in 5 different areas, you have to kill them all at the same exact time (within 1 minute?)
--Then you can kill the bloom of dooms, when all dead, a large spawn of Spawn of Devovorga will come, must kill it ASAP (dunno time). NOTE: after the bloom of dooms are dead, everyone in the area gets TP'd back up 1 floor, then you can go down again and kill the Spawn of Devovorgas.
--Some time after spawn of devovorgas spawn, all 5 bosses will respawn again but make sure all Spawn of Devovorgas are killed before killing any boss. Same as the beginning, it all must be killed in a span of time (1 minute?)
--Then more spawn of devovorgas will appear again, kill all
--Then kill all 5 bosses again at the same time (all spawn of devovorgas must be killed before any boss is killed)
--Then kill the bloom of doom and vulnerable cocoon to make the Devovorga spawn (must do this fast I think 5 minutes)
--Once it is all killed, Devovorga will spawn.
There are 6 key places
-one for each boss
-vengoth (devovorga place)