Less rabi is a major pain with au lag. The easiest way I've found is Zerg, if u kill him in under 20? Seconds u only get 1 interrupt to do usually. Hero and dump all abilities etc. I've spent a fair while trying it none boxing trying different strats (none boxing with really geared players and shammy spec'd for better interrupts) and ended up Zerged the first go. U might need better gear before u can do it or gets some arcane mages with speed pots to help out. Zerg is usually done as all dps, no heals and tank would normally change to dps too.

After the boss gets too low he changes in under a sec so if u have 300ms it's almost impossible to interrupt except via luck.