I have defended the balance for Floop, Melon, Biology Project etc, I never bought into the Druid hype.
Until now. This card is completely stupid. I originally thought you would need to stretch for a 7 drop to work with melon, but no longer. Honestly. cut Lich Kings from your deck, folks, because all you need is Melon in to this hitting your Malygos. If all fails, you are "left" with a 2 mana Alexstrasza. Thats literally worst case for this deck.
This could have been a random card rather than minion, and it would have been fine. Honestly, i could see a Malygos druid just not playing minions just to guarantee this hits. Yes, that includes Floop, thats how ridiculous this is.
Also, this works with Drakkari Enchanter. Completely broken, expect a nerf within 2 weeks