Hearthpwn

1. Ice Block - I hate those smug Freeze Mages cheesing the win off me at 1 HP

2. Conceal - It's infuriating when you can't kill a Miracle Rogue's Gadgetzan/VanCleef then they just finish you off

3. Entomb - The ultimate anti-fun removal; no deathrattles remain unscathed

Historically:

1. Mysterious Challenger
2. Big Game Hunter (I am so glad this was nerfed. It was just impossible to play big minions.)
3. Dr. Boom, PhD in balance-ology
4. (Dis)honorable Mentions: Leper Gnome, Mad Scientist, Nerubian Egg, Secretkeeper, Shielded Minibot

Currently in Standard:

1. Call of the Wild
2. Flamewaker (Currently this card is so much more annoying than Knife Juggler, at least for me, which is saying something.)
3. Sylvanas Windrunner (I'll admit that the pain is balanced out by the fun I have playing her myself, as well as the joy I get from Entombing her. Yeah, I'm a priest player, sue me...)
4. (Dis)honorable Mentions: Flamewreathed Faceless, Tuskarr Totemic, Flametongue Totem, Darkshire Councilman

1. Brawl

2. Conceal

3. Gorehowl or Doomhammer

Honorable mentions: Bloodlust, Thing from Below, Execute, Fireball, Entomb

Regarding Entomb: If looked at individually, it is a pretty broken card.  But as Priest has it, it completely isn't. We Priest players do miss a good AoE to make Entomb OP. I believe Entomb is way better in Wild.

1- Entomb (this card is so antifun. I know priest sucks right now, but they need cards that are a bit more interactive.)

2- Conceal (I had gadgetzan auctioneer, but I think it is conceal that actually makes that card stupid. it is just so non-interactive)

3- Cabal Shadow Priest (Now this card is situational, and sometimes even bad. But after turn 6, playing a card that has 2 or less attack can just lose you the game because of the tempo swing. That shouldn't be a thing.)

Honorable mentions: Reno Jackson, Shifting Shade, Ragnaros, Sylvannas

Looking at everything that I deemed annoying, the 2 big things that annoy me:

1: low risk high reward rng (rag, shifting shade card steal, Sylvannas, etc.) Having things that are rng reliant just feel bad because you have no control over it. Now rng can be fun and create great stories- but it shouldn't be so low risk for strong effects, like say Ragnaros is. I actually think discover and yogg are two good rng concepts. Discover has some elements of decision making, and Yogg because of the price (you have to get to turn 10), requires you to think and build around it (unlike auto includes in midrange like rag and Sylv), and is very risky. This is how rng should be made.

2: Cards that just take your stuff. They are HUGE tempo swings and value plays, and you can't really do anything about them. Priest is inevitably going to steal your big stuff: there is no counterplay. Shifting Shade can give you a huge value card for little draw back at high rng. You can't play anything against Priest with 2 attack after turn 5 or you could just outright lose the game. I know priest sucks and needs help, but part of the reason priest sucks is because a lot of their combos are so broken... but they are just so situational and inconsistent. If you cut down on some of the ridiculous priest cards, you could make better, more consistent cards that feel good to play against, and not so luck reliant.

Yeah I agree that aggro shaman is annoying, but I don't think it is one single card. I think it is the abundance of both aggression and burn spells/weapons that is too strong, not necessarily one single element.

1 entomb- don't take my doomsayer or legendary, and yeah, I know priest needs help and entomb isn't op  but it really ruins my day to see my strategy  fall apart to it and my opponent to use the card against me usually to win considering how long that takes and priest late game.

2 excavated evil- I play patron

3 2/3  spirit wolves with taunt- I always am just barely catching up on board and shaman plays these and protect one scary minion and so win the game.

1. Alexstrasza=Enables the least interactive deck of all time, and the most boring to play against, freeze mage.  Also a 9 cost card that deals 15 damage to the opposing hero and puts an 8/8 body on the board is broken.  

2. Mysterious Challenger=Enabled the statistically lowest intelligence deck in the history of the game, secret paladin.  Bots could get legend and maintain a 50+% win rate, no other deck controlled by a bot even approached that number.  As for the card itself...6/6 (1 less health than boulderfist), that usually draws and puts 5 secrets in play for 6 mana.  Since it is not legendary, 2 can be put into a deck.  MC, Boom, Tirion...yeah fun times.

3. Dr. Boom The most auto include card ever created.  A neutral that aggro decks would stretch their curve to fit, a card that has zero counter that doesn't result isn't a loss.  Oh and it also has that wonderful high RNG element with the boombot.  Also the first instance of pure power creep (over War Golem) in the game.