I really need to be more vocal about my complaints and compliments when it comes to games. The above Kripparrian video demonstrates the inability to play around an opposing mage when half their hand is composed of randomly-generated cards. (Like a number of my more recent Hearthstone-related posts) I agree with Kripp, but I'd like to address an underlying issue that makes the problem even worse.
Not long after One Night In Karazhan released, Babbling Book quickly rose to meme-worthy fame when Pavel's luck with the card helped toward winning the Hearthstone World Championship. Obviously this sparked a number of lengthy debates about RNG, luck and its consequences in competitive play, but I think Babbling Book by itself isn't that big of an issue.
|"This isn't even my final form!"|
The problem is that Babbling Book isn't by itself - far from it. We've seen true spell generation in mage as far back as GvG with Spellslinger, and it's been a bit of a recurring theme ever since. Even with Standard helping to rotate out too many cards of a similar type, there's still a lot of spell generation available... which is intentional. Blizzard based the Un'Goro mage quest around playing spells that didn't start in your deck, for crying out loud.
While it's a cool and fun mechanic, card generation in general is quite frankly a very powerful ability that I suspect Blizzard fails to fully realize. It's better than card draw, since it doesn't pull resources from your deck (which coincidentally even helps you win a fatigue war). Part of what kept priest (barely) alive during some of its weakest moments was its ability to capitalize on the power of an opponent's deck. A fortunate Thoughtsteal can change the outcome against many control matches, but often does little to stop aggressive decks. Why? It all comes down to what cards are available in the opponent's deck. Small, aggressive minions aren't really going to help that priest stabilize, where powerful late-game minions and spells typically will.
As you can see, the quality of a Thoughtsteal varies greatly depending on what your opponent is playing and what is left in their deck when you cast it. This range is far less varied in most of the mage card generators, as the pool is almost always restricted to mage spells. That's important to note, because mage spells in general are high quality and/or useful in most situations. Sure, there's a couple of stinkers in there (notably Shatter), but the overall quality of the mage spell catalog is slightly above that of most other classes.
I noticed this problem months ago after seeing the effects of (what I feel is the biggest offender of the bunch) Cabalist's Tome time and again, and noting to some friends about how high the quality of mage spells in general are. Don't believe me? Imagine if Cabalist's Tome wasn't restricted to mage spells; the results would be Yogg-Saron-level variance. Better yet, replace the mage-only clause with another class such as warrior and cry as your Cabalist's Tome produces Upgrade, Bolster and Stolen Goods (as a mage)! Making the cards generate mage-only spells isn't a restriction; it's actually better than entirely random.