Hearthpwn

People said Ravaging Ghoul won't see play? LOL

From WotOG it's Yogg. 

Praise Yogg. 

It's difficult to say from this expansion because there are a lot of cards that will introduce mini archetypes within a play style.

Barnes. Even a 50% chance of summoning thaurisan/Sylvannas/rag/cairne/Malygos

will lead to nerf cries everywhere.

Purify, hopefully an angel in disguise that could revive the class

Menagerie Warden is broken.

So I say Purify.

Quote from Click >>

I'm gonna go out on a whim and say that both Ironforge Portal and Spirit Claws have been under valued. As for the good Dr. though, I would say Menagerie Warden.Th

Zoobot well that's only if the effect goes off even if you have no creatures of the 2 other types.

edit: Arcane Giant can also be a good candidate.

Arcane Giant is going to be worse than Flamewreathed Faceless in Yogg decks, and I wonder if it wouldn't also be good in Miracle Rogue.  Get ready for a very unpleasant goodbye from Flamewaker as I think Tempo is about to have a pretty strong run.

Menagerie Warden is going to hurt, a lot, when it hits on Stranglethorn, DotFlang, DotFlame (will be a thing if Beast Druid is), or DotC.

Banres will be a very strong add for N'zoth decks.

Medivh's Valet and Enchanted Raven will both be solid.  

Honestly, it's not worth raging about, but [Enchanted Raven is one of the most blatant instances of powercreep in the game.  4 total stats and tribal synergy for 1 mana is outrageous.  People are going to rage when T1 Raven, T2 either of the mark spells or T1 coin 2x raven, T2 PotW.  That Druid, a class that was T1 forever, fell off for a second, and is already strong again got these very good cards is why Priest players are having a fit about the dreck they're getting.

The most overrated cards are the Hunter cards and Fool's Bane.  Cat Trick is a decent anti-spell tech; but it is very poor tempo in a meta in which decks that are not that spell-heavy (Zoo and Dragon Warrior in particular) can easily out-tempo you.  Aggro Shaman, which does run more spells, really doesn't care about the 4 damage and can wipe this card with AOE before it even acts (or stop it out with Taunts).  

Cloaked Huntress looks exciting, but Hunter's draw is already terrible, and when this does give you value, it will just put you into a topdeck situation ASAP.  Sure, if you can stick this on the board and play Lock & Load and have Secrets in hand or get it and Auctioneer on the board somehow, it could be kind of nuts.  Feels like a very clunky combo to me.

Fool's Bane is great anti-aggro, but worse than virtually every comparable option for Warrior.  It will suffer the same issue that all high-durability / cost weapons do - if it becomes popular, aggro and control will punish it with ooze and midrange will counter it with Harrison.

Menage warden.  Easy. 

Arcane giant for zero mana on same turn as yogg is awesome too. 

Arcane giant and barnes for sure. New warrior archetype (yes, another one) and a buff to freeze/rogue perhaps.

There are tons of cards that promote a cool deck to built around its abilities, but as far as there being 1 card that, on its own, is just an amazing auto-include for 95% of all decks there really isn't one.

That being said, I really think Moat Lurker is a massive game changer.

Quote from CGDPodcast >>

There are tons of cards that promote a cool deck to built around its abilities, but as far as there being 1 card that, on its own, is just an amazing auto-include for 95% of all decks there really isn't one.

That being said, I really think Moat Lurker is a massive game changer.

Arcane giant definitely has the capability of being very good, theres plenty of decks that can spam the hell out of spells already(tempo mage, yogg decks, miracle rogue), but the question then is, what do these decks cut.  The Yogg druid template probably has the most flexibility in terms of cutting a few cards to make room for the giants.

Quote from GiantDwarf0 >>

Quote from CGDPodcast >>

...That being said, I really think Moat Lurker is a massive game changer.

Can you explain why you think this card will be impactful? 

•  Warlocks can Power Overwhelming a non-1/1 minion, then Lurker it and get it back a turn or two later anyway.
• Rogues can Shadowstep it back if used on an enemy, but has the flexibility of doubling up a friendly minion for N'Zoth decks.
• It's the only viable neutral "destroy a minion" card.
• As much as it pains me to say it... Purify... ugh...
• Use it on your own Sylvanas to capture something, then get another Sylvanas a turn later.
• Destroy a heavily-damaged friendly minion after some trades, then get it back to full health soon.
• Sure, there are better class-specific methods of removal, but the flexibility of this one is awesome.

People hear have forgotten what the whole title of "dr." means. The "doctor" title never belong to cards that everyone thought were great, it belong to cards that everyone thought were going to be trashed and ended up changing the meta game to the extreme. This whole tread is just full of clueless people linking obvious cards that have already been voted good. The "doctor" cards were cards that were voted bad and ended up making everyone on this forum wrong, (which is a pretty common event.

Example: 

• GVG everyone rated Dr.Boom below troggzor and bam wrong.
• TGT everyone said Mysterious challenger was horrible because who would put all those 1 mana secrets in your deck and bam wrong.
• Naxx everyone said that sludge belcher was horrible because of the increase mana cost compared to senjin and they said the 1/2 taunt ooze was useless and bam wrong once again. 
• LOE hell, a massive amount of people on this forum said that a singleton deck for reno was horrible and wouldn't see play and bam extremely wrong. 
• WOTG everyone was saying that a 3 mana 1/5 was horrible tempo and would never work, and now this card in combo with others have made zoo the power house today.

All this thread has is people posting obvious stuff, the cards that are so obvious, the one that these forum always list or write about nearly always come out as average. There is a massive chance that the doctor hasn't been announced yet. Most of the "pro players" that people listen too have a huge incorrect rate when rating cards. Just look at Trump, whenever that fool says a card is bad, it always comes out to be the new doctor.

Basically doctor means the card that everyone doubted and no one saw coming. Not a card that everyone freaking agrees with and just instantly think its good.  

Barnes, Medihv's Valet and Raven.

Moroes in zoo decks!!!

Quote from ambershee >>

Quote from GiantDwarf0 >>

Quote from CGDPodcast >>

There are tons of cards that promote a cool deck to built around its abilities, but as far as there being 1 card that, on its own, is just an amazing auto-include for 95% of all decks there really isn't one.

That being said, I really think Moat Lurker is a massive game changer.

Can you explain why you think this card will be impactful?  Using it on your own deathrattle minions is clunky because the best deathrattles are too expensive to play in the same turn (Cairne, Sylvanis).  Using it as additional removal is expensive, particularly if you intend to silence-combo to remove the deathrattle.  The most obvious I application I can think of is as a worse, slightly overcosted neutral Sap, which may be useful in some instances (arena particularly), but is very situational.

It has it's uses. Depending on how the metagame swings in future, it could be used to remove enemy minions that have beneficial deathrattles. I could see it being played in deathrattle Rogue, but it combos well in specific deck archetypes - look towards cards like Dreadsteed, Twilight Summoner, Nerubian Egg and to a lesser extent, Darkshire Librarian (risky), Unearthed Raptor, potentially Southsea Squidface.

There's value there, but it's going to need a very specific deck. The real problem with it is that it's slow.

Quote from Battenberg >>

Menagerie Warden would be my guess as part of the beast druid deck Blizzard have been pushing from the start. Stranglethorn Tiger on 5, which is very hard for most classes to remove, gives you 10/10 of stats for 6 between 2 minions, one of which has stealth. With Enchanted Raven, Mark of Y'Shaarj, and Wildwalker that deck's going to be a real pain to beat; it may even be able to consistently pull off Druid of the Fang plays, making Menagerie Warden even more crazy.

 I think the curator might provide the "drawing a murloc" consistency to make mill rogue competitive. And when it works, the only counter is to kill it before it mills your win conditions and blows up a 30 damage fatigue bomb in your face.