Posted this in bug forum
Never seen this before ever, don't know if this is a common issue but
Thought it was the funniest thing ever and wanted to share it
Tried to capture but couldn't hopefully someone did
Is there a lore reason behind this phenomena :p
Bugs happen, man.
Just a bug, it's happened before with other bosses in both dungeons and raids.
Usually what happens is there's a full wipe, but someone had a Raise cast on them and they stand back up instead of returning. If the timing is just right, the boss aggros them as the arena unlocks. The poor fool panics and runs to safety just as the rest of the team gets to the arena door. Boss aggro jumps from person to person as panic spreads and hilarity ensues.