I'm currently looking on youtube for someone who passes the fight on PotD without cheesing. I'm curious to see how it's done. Here is the only one I've found that plays on PotD and he uses a similar tactic.
Oh, there is a guy who passes the fight... lvl 12 or 13 party though (!), and four tanks - a monk PC, Zahua, Eder, Pallegina + Durance and the Devil
These are all the PotD non-solo videos of this battle I could find. If anyone thinks they're very tough, record a video of how you pass this battle on lvl 8-9, I'll be very interested in seeing it.