Everybody were going nuts about Purify but I think the Menagerie Warden will be the real problem.
A bad card, or even a bad class, can be avoided, a trap for those unware to recognize it's flaw Something OP, however, will be abused and mold the metagame around it.
I don't know if Druid has all the tools to consistently  curve out a 5 drop into the Warden, but if he does, it's pretty much GG at this point. A Call Of The Wild which come 2 turns earlier.
Still, Purify got the limelight. I said it once and I'll say it again, I much prefer 8 balanced classes and 1 shitty one than 1 Op class towering above the rest.