generally its a matter of mangetment of units and power.
I never used to have problems with firedancers(i use past tense as i have still not got all the cards for my pure frost pvp deck again(but had in the old battleforge)). it is a matter of countring it. firedancers have to low life to really be a danger to a M counter that is not a small unit, i would proberly use something like a razorshard or aggesor to deal with it
you do know you can also use the aura of corruption against the enemy even if he plays it, the only anoing place he can put it really is at wells and orbs but all you really need then is remove his ground precense and the aura is useless, and it is dam expensive to use and easy to counter with cheap units, just spam something like northguards or heals and you kill his units and yours stay alive, it is not so hard as the damage is spread over all the units in the aura, eighter mass it making the damage negletable or cast expensive units and move them out of the aura