Hmm, that's how I did it too, kill the sandstorms and bats first, then the ants to open the way. Not killing them at the same time. At least we weren't coordinating to kill them at the same time. So we wither got insanely lucky, or kill order matters not final mob kill time. Try that strategy and see how it works out for you. I think I will be going back in to help a bard friend of mine soon and I'll pay closer attention to give you exact details.