Unfortunately, this one will be shorter as the reveal season was much shorter. As always, this is the following review score (which has become pretty standard these days for most reviewers).
4: One of the best cards in the set, a class staple, or both. 3: Very good card that will see a lot of play. 2: An okay card that might see some play here and there. 1: A card you're not likely to see in any decks, if at all.
Overall, I think MDF is a less powerful set overall than Scholamance. But, the reintroduction of the Old Gods will have a massive effect on the metagame until they rotate. That, alone, is probably enough to make this a powerful, and memorable set. Therefore, I think it makes sense to evaluate the Old Gods first.
C'Thun, the Shattered - 3 This was the Old God I was most excited about, but ultimately, I don't think it will see as much use as many think. It. Is. So. Slow. Very few classes have the tools to survive long enough to assemble C'Thun, then survive long enough to draw C'Thun and play it. Cards this slow HAVE seen premier, competitive play before (Rin, the First Disciple). While I definitely think there will be a C'Thun deck, I don't think there will be as many as there are of the other Old Gods.
Y'Shaarj, the Defiler - 3 This is one of the reasons I think C'Thun will see less play. Many of the same decks that can play C'Thun can also play Y'Shaarj, and Y'Shaarj is more immediate. He can be hand and board refill. He can be burn damage. I think there is enough parasitic support in this set to allow for Y'Shaarj to be a viable win condition in a number of classes.
N'Zoth, God of the Deep - 3 I think this is the least powerful Old God, but that doesn't make him bad. I see this as top end for a variety of defensive AND tempo decks (remember, there was a time when Varian Wrynn was the top end in tempo warrior). Unlike Y'Shaarj, this is a card that will continue to get better as more cards are released.
Yogg-Saron, Master of Fate - 4 I'll start by saying that I think this card will get nerfed. I don't even think it's because of the random pyro blasts (which...why?!?). OG Yogg had to get nerfed. Puzzlebox got a handful of surrounding cards nerfed. And this card is better than both. Almost none of the options are bad. If your deck plays spells, this is going to go in it. And you'll be happy. Your opponent won't be.
First, I want to say that I love this mechanic. It's so interesting, and it requires a lot of thought both in deck construction and in game. That said, I'm not sure how powerful it is. It shares similarities with Imprisoned, which was inaccurately rated by basically the entire community. So, I'm inclined to think that Corrupt will be better than people expect. That said, not all corrupt cards are created equal, and some are much better than others.
I don't think anyone will be sad that Demon Hunter didn't actually get a very good set. Unfortunately, the good cards that it did receive are VERY good. Il'gynoth and Bladed Lady slot right into Soul Fragment DH, and become some of the best cards in that deck.
There is a good smattering of token stuff...but that deck is still bad because Nethrandamus isn't a win condition. DH also received a healthy amount of aggressive cards, like Felsteel Executioner, Acrobatics, Stiltstepper, and Dreadlord's Bite. It's hard to say which of these will see play and which won't. There is already a lot of competition in the archetype, in terms of minions, card draw, and weapons.
The Outcast synergy cards don't seem like real things to me. And Zai is a fine card, but I don't think you're playing him absent something kind of gimmicky with Yogg.
Druid received a mixed bag of cards. If there is a successful Druid deck this format, I think it will look substantially different than the Guardian Druid that was recently nerfed. Fortunately, Druid is poised to take advantage of a number of the Old Gods.
First, there is clearly some manner of Spell Druid, which looks like it will be different than the Spell Druid that focused on Glowfly two formats ago. Kiri and the Eclipses, Umbral Owl, and Cenarion Ward all look to be good fits here. It will be interesting to see how that deck looks to close games: With Yogg, or with Survival of the Fittest scaling minions like Carnival Clown and Y'shaarj. Whichever the path, I think this is most likely to be the strongest bet for a top tier druid deck.
That said, I think there's also a more than fair chance for a big druid deck. This deck hasn't been popular for 2 formats, but it never had a top end like N'Zoth or a chonky elemental like Fizzy. Big Druid will have problems with Priest, just like Big Warrior did this format. But, if Priest moves in a different direction, there could be space for Big Druid to make some noise.
There are also token cards. Greybough is a fine card for a deck that doesn't exist right now. Faire Arborist isn't even a good card.
I'll be honest - Hunter got 1 good deck. The deathrattle deck (although I want to love it) and handbuff deck are not going to work. Therefore, the secret cards will receive good ratings, the other cards won't.
Mage's set went in two directions: Secret, and Elemental. While the support each got is good, I don't think there is enough for either deck.
Confection Cyclone is a great card, and Grand Finale is exciting. But there are not enough playable elementals. I think it's more likely we see the current Cyclone Mage merely incorporate the Confection Cyclone - Elemental Allies package. It will probably forego Grand Finale. But hey! At least there's Yogg!
Secret Mage is only as good as the secrets in standard, and I don't think the current secrets are impactful enough. The support cards, however, are solid.
I understand the spreadsheet floating around that says Deck of Lunacy will yield mostly positive results. But why are you playing this? Transforming the good cards in your deck into question marks is a meme. This is Mage's Renounce Darkness.
A few classes got the nuts, and paladin is one of them. Overall, I think Librams will still be the centerpiece of every Paladin build. But they diverge a lot after that.
Pure Paladin got a major buff with an actual end game in Yrel. Dude Paladin got a bunch of stuff, although I wouldn't be surprised to see it simply become a Pure Paladin variant.
There are also opportunities for N'Zoth, Yogg, Y'shaarj, and even C'Thun variants. Hammer, Gryphon, and Redscale are N'Zoth friendly. Gryphon crosses into Y'Shaarj territory. Libram of Wisdom and Yogg are best friends. And Paladin might even have enough sustain to get it to C'Thun. There should be quite a bit of experimentation in this class.
Oh, and Highlander is an even more reasonable option now.
Priest got the meganuts. There's scarcely a bad card in the bunch. It also received so much mana cheating that the possibilities are wide open next format. It can play most/all of the Old Gods. It has some new Res Priest support. It still has Galakrond. Priest is going to be strong.
Rogue either hit big or whiffed this set. Luckily, when it hit big, it nailed it. It's hard to imagine any Rogue deck in the future not playing Foxy Fraud or Swindle. Tenwu is maybe more of a puzzle, but is no doubt very powerful. Cloak of Shadows will likely find a home somewhere. Buying a free turn is always powerful in Hearthstone.
I may be on an island here, but I think the whole "shuffle into your deck" thing won't work, and this includes C'Thun. I understand that Strider was a good card, but Ticket Master is worse. It's still okay enough to maybe see some play. But the rest of the support is just a gimmick. Shek'zara would be a very good card in other classes, but I don't think Rogue needs it, especially when Swindle is in the same set.
Secret Rogue got big buffs from outside the Rogue class set.
I think people will be pleasantly surprised by what Shaman received. It received a bunch of universally good cards that can benefit whichever archetype you decide to play. Better early game minion and card draw in Custodian. Early game removal that doesn't overload. And control end game in the Old Gods. And it picked up some more totem support for good measure.
I think the big winner is Evolve Shaman. The deck had good winrates when it drew Knuckles, but awful winrates when it didn't. Custodian goes a long way to curb that issue. It also got a powered down version of the Desert Hare - Evolve days with Revolve.
I'll note that I believe I am higher on a demon warlock than many reviewers. Similar to Master's Call, Free Admission is too good not to generate and archetype. Wicked Whispers may be worse than Mark of the Lotus, but there is a lot of room to be worse than Mark of the Lotus and still be a very good card.
More than that, Free Admission also works with bigger demons like Enhanced Dreadlord or even Siegebreaker. Cards get a lot better when you discount them 2 mana and can tutor them from your deck.
I also think there's a lot of opportunity for late game warlocks using Tickatus. Heal is still and issue for Warlock, but there is some moderate heal in the neutral set that thankfully also plays nice with Y'shaarj. You're probably not fitting Man'ari Mosher into your control deck, but the option is there for you.
Likewise, I think Deck of Chaos has some real potential. Yes, it is worse than Luna's Pocket Galaxy. But Mage also didn't have Plot Twist. Even if it isn't a combo deck and merely turns into playing cheap big boys like Batterhead or Carnival Clown, I think that can be a successful deck.
The best part is, there isn't a single awful card in this set for Warlock. So that's something.
Warrior was obviously hard pushed in a menagerie direction. The nice part about menagerie is that it's very open ended. As such, I think some variant should become successful. There is a pretty obvious tempo build, but I wouldn't be shocked to see a taunt build actually becoming the most powerful. The fact that the new Amalgam is a taunt minion is pretty great for Into the Fray and Armegadillo.
And since Warrior is Warrior, I wouldn't count it out for any of the other Old Gods either. Although, Y'shaarj is a bit of a strech since Warrior didn't receive a class card that works well with the Old God.
Carnival Clown - 3 In a lot of ways, I see this card as a Nomi you can play multiple times thanks to Y'Shaarj, but you don't need to work as hard for. Before, this ability was limited to Druid and Priest. Those classes can still pull this off, but now other classes can as well (Warrior, Shaman, Paladin).
Nice analysis, although I have to say I strongly disagree regarding Oh My Yogg!. This is a mini-counterspell for 1-mana and will see play, especially in wild (Odd Paladin)
That's fair. But I only rate for standard, not wild.
And Oh My Yogg! is quite a good card. Secret Paladin is not going to see play though, IMO. I'd be very doubtful if OMY sees play in standard unless it's created by Wand Maker or Spellkin. Thus the 1.
It's quite likely that it won't see immediate play in wild. But it might depending on the meta as it is a tech card. Never Surrender! was run by Murloc Paladin to protect against AOEs like Breath of the Infinite, if the new meta has many spell-heavy decks, Paladins might tech in Oh My Yogg! without any other secret support.
Grand Finale seems super underrated. Play elementals and doomsayer on seven and then win against many classes on 8.
Unfortunately, I just don't think there are enough playable elementals. I think Grand Finale is a good card, so there's room to improve. I just don't think it's a good card in the current context of what is available.