The dragon's fury combined with the gas can weapon in MvM are absolutely broken. I did MvM the other day, and the pyro alone pushed out 130,000 damage (who needs demomen then?)
It worked so well in fact, I can day surely that all you need is a team full of dragons fury+gas pyros, a med, a engineer maybe, and one scout. So que up the MvM before it gets fixed because it's honestly so broken.