Hearthpwn

I don't know if anyone's made a post like this, but I'm curious to know what card was most influential to each class in your guys opinions.

For me it goes something like this:

Priest: Hands down Twilight Guardian. It actually made a new deck type viable, dragon priest, albeit one whose strength greatly varies but is new.

Paladin: Think we can all agree that Mysterious Challenger is pretty much the mvp for pally from TGT. They made paladin secrets playable.

Warrior: In my opinion, warrior didnt really get any card that really influenced their deck archetypes. Patron pretty much didn't change, control added Varian Wrynn, which probably would be my choice, since his battlecry is amazing.

Druid: Darnassus Aspirant and Living Roots get my choice. Not only did they significantly help druid with their ramp, both cards fix a lot of the early game issues that druid has.

Shaman: It's a toss up between Totem Golem and Thunder Bluff Valiant. Both made totem decks viable and made shaman's strength increase from the rut they were in before.

Mage: I'll really just leave this up to you guys. Mage is the one class that consistenly always gets good cards and as has never honestly had weak cards. Rhonin is absolutely amazing in tempo mage, Effigy fixed a lot of the predicatability of using Mirror Image

As for Rogue and Warlock, I honestly can't think of a TGT card that made it's way into any existing decks. Maybe Wrathguard and Undercity Valiant. In a way they probably got the least out of the expansion.

You forgot Wyrmrest Agent and Holy Champion for priest. Besides that, I agree with everything.

Dreadsteed deserves consideration for Warlock.  Polymorph: Boar is contender for Mage.

Quote from LunacyHS jump

You forgot Wyrmrest Agent and Holy Champion for priest. Besides that, I agree with everything.

Wyrmrest Agent is a strong card, but without Twilight Guardian it's effectiveness is sorely limted. As for Holy Champion, its a nice four drop for priest but it suffers from the same weaknesses that make Light Warden not played and overall hasn't seen much play.

Quote from DarthJaraxxus jump

Dreadsteed deserves consideration for Warlock.  Polymorph: Boar is contender for Mage.

Honestly, I see dreadsteed as more of a gimmick because once you see it, you know what type of shenanigans your up against and more often then you can play against it. Plus, with decks like Patron, filling the board with 1/1's isnt the greatest idea. As for the new polymorph, I liked the direction, but overall its really not worth it. 

Well Zetalot has been using it and has been #1 legend quite a few times with it in his deck, so it can't be that bad. http://www.twitch.tv/zetalot/v/15495923

I know he's been using them (Im actually watching his stream), but just because a pro uses a card doesn't mean its faults go away. 

Sure, but that also doesn't mean that therefore you shouldn't run it and if it's able to be viable in top 100 legend it's a card to consider. Priests are a naturally reactive class with tons of silence bait and you're comparing a 1 mana 1/2 to a 4 mana 3/5 lol.

Wrathguard has been pretty amazing for me. I built this deck centered around utilizing his effect and it's been dominating.

Also, you didn't list Hunter. :P

Effigy is the card for mages

Justicar Trueheart for the warriors.

For rogue... it's hard to tell yet. Beneath the Grounds is the only one I have seen atm, well, and Bucaneer.

Dreadsteed, well, it hurst, but I really think is the true TGT warlock champion (that coming from a 4 mana 1/1 is pretty hardcore).

The others are pretty much what it has been told (with darnassus over roots maybe and totem golem over thunder bluff).

Agree with the list besides Wrathguard, also
I'd say Wyrmrest Agent  and  Holy Champion as LunacyHS mentioned for priests,
Bash for warriors,
Powershot for hunters, I'd say Ram Wrangler and Bear Trap made people play less aggro oriented hunters, but that's just my opinion.
Personally I found Fearsome Doomguard to be my new favorite card for warlock, for me this was the best new card for the warlock class

Wyrmrest Agent for sure needs to be on the list.

Mage: Polymorph Boar: this card is great in a tempo or flexible mage deck because it fills the place of polymorph and can also be 4 damage to the face if your going for lethal. A great card. I really wish Fallen Hero had been a 2/3. Rhonin is a beast in spell deck. 

Paladin: I know everyone will say it has to be Mysterious Challenger, and I can't argue because it has spawned the dominant new deck that everyone is running. But I will say that that deck has vulnerabilities and I am not sure it will be viable long term. My favorite card that Paladin got is Murloc Knight. This thing fits into many different paladin decks and can snowball into ridiculous value.

Shaman got the 3 totem cards and that made totem decks viable. 

Warrior it's definately Bash, that card is great value and fits in almost every warrior deck. I stopped running execute because of that card. But I still want to figure out a deck that could use alexstraza's champion effectively. That card is just amazing but just does not fit into any warrior deck properly. Dragons are slow and that card is amazing fast pressure, I guess it could simply be used removal and a possible value play, but I want to make more of it. Of course you have to mention Varian Wrynn. The 1 card combo and win condition unto himself. 

Priest it is Wyrmrest Agent and Twighlight Guardian. 

Hunter got a whole new midrange value deck with King's Elek and Ram Wrangler, too bad face hunter still seems more viable. They also got a gimmiky lock n load deck. They got a lot of cards that looked good but then in practice fizzled, I'm looking at you Brave Archer, Powershot and Bear Trap. 

Druid really did well, Roots, Aspirant and Combatant are all great cards and fit into a variety of decks. Combo, token, ramp, beast druids all looking viable. 

Warlock, I am not sure warlock got anything that will last. Wrathguard is a gamble, dreadsteed an interesting but limited deck, I thought Gormok the impaler might become a staple in zoo, fist of jaraxus in a discard heavy deck (though I think you need one more card that wants to be discarded before you can chase that archetype), overall I don't see warlock as getting much help. 

Rogue almost got a pirate deck, that is dangerously close to becoming a thing. 

Quote from LunacyHS jump

Sure, but that also doesn't mean that therefore you shouldn't run it and if it's able to be viable in top 100 legend it's a card to consider. Priests are a naturally reactive class with tons of silence bait and you're comparing a 1 mana 1/2 to a 4 mana 3/5 lol.

I'm not saying you shouldn't run it, I'm just Saying it still suffers from the same drawbacks that made a smaller version of it not runnable.

my choices:

warrior:  Justicar Trueheart.  I dont know if I would put Varian as most influential, it is probably the most tested, but whenever i see him played, hes not really something i would consider risking losing a turn if i m behind.  To be honest, neither is justicar, but if i m behind, i rather gain 6 life on turn 10 than draw 3 cards and hope to god something with taunt is put into play.  that and the 4 armor makes a huge difference in the long run.

hunter:  Ram Wrangler and King's Elekk.  We have seen midrange hunter, but I think this card really pushes for the deck to be popular again somewhat...... King's Elekk becomes a 2 for 3/2 (which is average stat for a 2 drop) and a winning joust means you probably dont have to dig for a mid to late game.

mage:  Effigy.  It just makes everything stickier.... even when you hex or polymorph a target.........

priest:  Twilight Guardian.  wyrmrest might give it another 2 drop, guardian gives a dragon that matter.

rogue:  Cutpurse and Beneath the Ground.  For cutpurse, games i have seen him in, getting one coin matters.  i think the potential is there.  as for Beneath the Ground.... the surprise factor scares people.  

shaman:  Healing Wave.  I think this card did a better job reviving Shaman as a possible class than thunderbluff valiant.  valiant inspire a new deck type but healing wave give possibility to midrange and control shaman.

druid:  Darnassus Aspirant  This gal demands answers.... like how many 2 drop you can think of that can say "Stop me or I will steamroll you"  not even knife juggler can do that.......

paladin:  Murloc Knight and Mysterious Challenger.  Most annoying card to deal with in arena with the most annoying card to deal with in constructed.  althought what challenger brought out gets predictable, its the fact that you can't avoid it that makes it scary.

warlock:  Dreadsteed.  its just begging to have a deck built around it.  i think it gets better the more set we get.... 

Quote from Ricinaz jump

Rogue : 

that card is garbage lol

Totally disagree on Cutpurse and Totem Golem. 
Shaman is all about the Tuskarr Totemic