For people trying out this achivement here's a link to our kill
http://www.youtube.com/watch?v=_9J7G7H7Wlo
the only tact is basically what says in the description, form 1 big from 2 small and kite it into the big one to slow the growthrate, once the first blog is at 4 stacks, we had our hunter take over the kiting of the new big blog and made it with 0.2-3 sec to go
took plenty of wipes before we got it, always helps to get lucky sometimes since we did everthing perfect except for those last few sec when hell broke lose