Hearthpwn

For me the problem is that several of the other lines (warlock and Pali) consistently complete turn 4 for a 7/7 with a game altering effect. Try controlling a paladin that spams 1 cost stuff early (Pali has tons of generation), gets a 7/7 turn 5 that turns any silver hand recruits into 3/3 (and likely has two since the deck plays our 1 cost your next hero power costs 0 friend as part of the chain completion...) then spawns 2 3/3 minions per turn for two mana, has spell control like omy and tons of low cost cards that now constantly fill the board with upgraded 3/3 minions. Please tell me how a priest replies turn 6 and 7 (with any hope of staying on curve, not burning out of cards, and not needing a literally perfect hand to survive. Forget completing the questline, priest is happy to MAKE IT to turn 8 (especially because they lost a card on the quest line, and only got it back if they played on curve 2,3,4 which again requires either perfect draws, of has allowed the paladin to melt your face turn 5.

Dont even get me started on warlock. Darkglare warlocks can get their quest line completed turn 4. Which means a turn 5 play 7/7. that will allow the warlock to low cost burn you to death by latest turn 6 (turn 7 without coin - even reno priest may not have time to even play reno - and even if you do, the warlock is drawing cards by burning you, so you are still gonna melt, even back at 30). Darkglare makes most of these plays free (or 1 mana) and many of the early ones don't even put the warlock at risk for aggro (lose 5 life, gain 5 armor etc.). Literally (worst case warlock goes first): turn 1, questline, turn 2 hero power, turn 3 dark glare + 2/1 draw and lose 2 life + 1/1 hero power free + hero power. Quest line completes both heros now at 27. Play lose 5 life gain 5 armor, play 3/2 lose 3 life. Quest line 2 completed play now stands opponent at 24 warlock at 25 with 2 armor, warlock with a 2/1, 1/1, 1/1, 3/2 in play, one mana open, 3 cards in hand. Assuming those 3 cards aren't crazy lucky (if they are, the quest line finishes here), the warlock can easily finish with a draw and self burn turn 4 (even if dark glare dies). Now the turn 5 7/7 is happening. The warlock is above 15 (probably well above counting armor) and had tons of early minions so is exceedingly unlikely to have been overrun by aggro, and can, turn 6, draw and burn through their deck at the other players expense (with coin, I've actually seen warlocks play the 7/7 turn 4 and kill me turn 5).

Anyone who thinks a questline that requires 7 distinct plays totalling 35 mana with restrictions on the timing of the plays (you need to draw and cast your 2,3,4 costs BEFORE the 5,6 costs count, so if you don't get fansastic luck and get a hand perfectly on curve (or play a discover deck and get reasonably lucky) you will be foddering plays saving yourself that dont count for the quest. Even when the quest completes all you get is a 7/7 fof 5 with the chance to draw a block able win condition (mutanus eats the 7/7, tickatus kills the shard, omy, counterspell, illucia, the list goes on) that costs 10 mana....

The questline is hot trash in wild and at best middle of the road in standard. 

Pointing to other problems doesn't actually discuss this one. Yes, there is a problem with librams. There is also a BIG problem with oh my yogg.

A few replies to the above:

1. Making the effect truly random (any spell any level) would actually be a buff to oh my yogg in higher leagues of standard (where knowledge of the limited card pool makes it at least semi predictable).

2. In terms of it being a mage spell, that makes the card pool per cost tiny (and if it's any cost then coin basically turns oh my yogg into a crazy burn to the pally or their minions- likely and in doing so will end all play of oh my yogg), either way, yogg becomes instant garbage in standard and still has the same problems in wild.

3. Saying ppl can play around counterspell fundementally understates it's impact. Again I was secret mage in legend (standard) last season and lots of players messed up their turns trying to play around the possibility of a counterspell (I would generally avoid playing my 2nd counterspell until an emergency or until endgame because triggering the second counter would allow my opponent to stop making poor plays out of fear - - and this is again in LEGEND). That said, counterspell is a fair (really annoying but fair) card. Many spells it counters cost less than it, decent play choices prevent the losses of your top spells, and there is an implicit requirement of a secret heavy deck (otherwise the fact it is a counter is obvious and it's value is defeated - - and this is undesirable in many mage builds).

None of this is true for oh my yogg. All paladins have 3+ diff secrets they want to (or would be happy to) play (especially with sword being able to remove them from deck to prevent later game draws) . Almost nothing (unless you are lucky enough to have the coin) costs less than oh my yogg (so it rarely represents a loss of mana).

4. The idea that SOMETIMES oh my yogg helps the spells caster represents a complete failure to even attempt to see the card clearly. It's not about the times it looses a game for the pally or the times it wins the game for the pally, or anything in between. It's about the fact that it is a 1 mana counterspell without a strict (or even probable) penalty. 

 Also I have tested coin in wild, twice. The first time I lost all my mana to destroy my own minion, the second time I lost all my mana and healed for 8 health.... Never testing with coin again in wild, it cost me the game both times. 

A few things. First zero sum game doesn't mean bad outcome it means any gains come at the direct expense of one side with expected value zero (its a game theory term in economics) two card examples: If I play a minion with some benefit to me that would not be zero sum, it would be strictly beneficial to me. If I cast a truly random spell, with truly random targets on a truly random board that would be zero sum (yes I know there is no such thing but this is a thought exercise). The effects of oh my yogg that mirror counterspell are in no way zero sum (numbered 1-4 by me) effect 5 is (or is at least close to on one side or the other). In order to 'effectively' counterplay oh my yogg, you need to know that the secret your opponent has is oh my yogg (otherwise you are restricting your play to say 5 cost spells if you are looking for desirable effects - - and even then there are still decent odds you are targeting a board clear and get a buff or visa versa - - then oh my yogg doesn't trigger and you just badly misplayed your turn). This idea that anyone at any rank can just waive a magic want and perfectly counterplay counterspell or oh my yogg is simply nonsense (I was mid legend on a secret mage standard last season and people mucked up turns for fear of counterspell all the time - it's why secret mage had (and has) noticibly better win odds going second, because coin gave a free counterspell test).

Wow... I just noticed you literally said 'keep the coin to do so' so basically you are conceding that the card is a problem the 50% of the time you don't get the coin.... Even that is enough to mandate a nerf... And by the way testing oh my yogg with coin works as you said because of the small zero mana card pool. Try testing with coin in wild :P bad idea. 

Lets refocus to my actual advice:

Oh my yogg is a 2 mana cheaper counterspell with an effect that (unless you happen to go second and are playing standard) is zero sum (again not saying bad, saying expected value zero with someone getting hurt). Paladin is not weak at the moment (and secret paladin is a thing) so nerfs are likely to improve odds for other classes - which is desirable. 

My proposed nerf was: keep oh my yogg the same in current effects, have it add a 1 mana card that reads: discover a spell from your class to the casters hand. 

All effects but 3 from my OP remain the same and reversing 3 means spending the same mana that was spent on oh my yogg. 

I wanted to tackle this in a few parts:

First let's do some analysis on counterspell:

Counterspell is a 3 cost rare spell with has the following benefits (in no particular order):

1. Secret synergy 

2. It's existence forces your opponent to either make suboptimal plays when ANY secret is in play, or to risk losing a key spell - for more advanced players, usually the suboptimal plays route. 

3. It costs your opponent a card 

4. It costs your opponent mana (unless they have the coin or a zero mana spell handy)

Now let's compare to oh my yogg:

Oh my yogg is a 1 mana epic spell which covers all 4 of the above PLUS

5. Casts a random spell with random targets 

A few notes: First, effect 5 by itself is considered a fun and minorly beneficial effect on any card. At the worst it is considered zero sum and entertaining to many players. 

Second oh my yogg is epic, counterspell is rare, so it should be modestly stronger. Even discounting effect 5 as zero sum, oh my yogg costs 2 mana less than counterspell for the same 4 effects. That is radically stronger (in no way proportional the usual rare to epic power boost) than a reasonable card should be. 

Taking all of the above into account I definitely think a nerf to oh my yogg is in order. Furthermore any nerf to the card must target one of its 5 strengths (you can't target cost as seeing a paladin play a 2 cost secret would be a dead giveaway that would defeat the purpose of the card), or must completely rework the card. As a general rule I think nerfs should attempt to preserve the spirit of the card while roughly balancing it with other cards in similar slots. If this is impossible then and only then something more radical is needed. With that in mind let's analyze the 5 current effects of the cards and see what nerfs would be possible without fundementally altering oh my yogg:

1. Not much you can do here. By its nature it's a secret, and will share secret synergy. 

2. It is supposed to serve this purpose (in fact I would argue that this is its primary function) so I will look elsewhere for nerfs. 

3. Several options here: let your opponent draw a card OR give your opponent a 1 mana discover a card (more thought could probably present many other similar options to nerf trait 3)

4. Refund your opponent the cost of the spell OR charge the paladin the cost of the spell (by giving them less mana in their following turn). 

5. Make the random effects generally positive to the caster / negative to the paladin (in the vast majority of cases) 

Now my opinions:

I think oh my yogg is meant to cause craziness so I don't like the idea of a nerf to 5. If the nerf is gonna come to 4, I would favor refunding the mana - - that would emphasise its craziness effect and make it weirder to counterplay (do you really wanna test with coin if you will get 0 mana back and may cast a spell that eats all your mana?). If the nerf is gonna come to 3, I favor the discover a card option (I think it quite nicely plays into the randomness mechanic of oh my yogg, it doesn't help decks that want to cycle for certain cards, and it requires the player triggering oh my yogg to spend the same 1 mana that oh my yogg costs to replace the card - I see a certain elegance there). Between a nerf to 3 or 4, I favor the nerf to 3 (in the form of the discover a card option) though I would be happy either way.