@Marioland  
I did no such thing. It has been 4 this whole time.

@Ledvi  

 
You changed the attack value on me, didn’t you? I could’ve sworn it used to be 3.
 
Still doesn’t make it playable though, since Ragnaros still does a much better job at eliminating minions instead of merely crippling them.

@Marioland  
Wait a minute. Shadow Word Pain requires the target to have 3 attack points not 4. 4 are minion’s sanctuary.

@Background Pony #3ECA  

 
That’s basically what I said, just several paragraphs shorter. I approve.

@Marioland
 
Ragnaros is just a better version of this and doesn’t get the silence keyword involved.

@TheDeinonychus  
It’s not as powerful as you’re making it out to be for quite a few reasons:
 
1: You’re probably not gonna have the mana to do anything else, so it’s pretty much going to be your entire turn. That’s a lot of lost tempo there, due to reason 2.  
2: It provides no real board presence unless your opponent attacks it directly.  
3: It’s effect is random, and therefore not very consistent. Cards based nearly entirely on RNG don’t prosper, (barring the odd exception like Yogg Saron, which is run as a Hail Mary anyways).  
4: It’s really not that hard to remove it in the late game for most classes. Hell, its attack is weak enough for Shadow Word: Pain to kill off a 9 drop for a mere 2 mana!  
5: The more minions your opponent has, the less effective Thorax is. He can’t silence everything, so just playing multiple minions per turn can make him nearly useless.  
6: Silence may be powerful against select archetypes that rely heavily on buffs and deathrattles, but a lot of decks run a lot of Battlecries and effects that just aren’t worth silencing or rely on spells to win. This is a lot less useful against those.
 
In essence it’s a sluggish, more costly version of Eadric the Pure, and all Eadric ever saw was fringe play. Poor Thorax wouldn’t even get that. Thorax is too random, too slow, doesn’t place a usable body on the board, and is easier to dance around than Ragnaros (who, mind you, is 1 mana cheaper, usually kills the target it hits instead of merely crippling it, and can provide significant damage to the face). Thorax is simply outclassed.

@Marioland  
Silence is a very powerful ability, considering a lot of high cost cards have relatively low stats, but very good extra effects. While it may be random, the fact that it happens on every turn means your opponent either has to sink everything into removing this card from play, or a large portion of his cards are effectively useless. Add that to reducing the target’s attack to 1 means that even those cards with good stats are potentially reduced to over-priced turtles. A card like this removes any pretense of strategy and reduces the game down to who has the best luck. Sure, it could hit a worthless minion, or keep targeting the same one each round, but that’s all based on luck. And with 9 health, you can be pretty confident that this card will stick around for a while, barring any instant removal.
 
Without spending an instant removal spell or minion ability, this card is almost guaranteed to get it’s effect off twice. For a card with that much health and that powerful of an effect, it’s value is way above it’s actual cost. The fact that it can’t attack is a non-issue. Just set it behind a couple beefy taunts and you’ll get three or four uses out of it.
 
If anything, changing it to take effect at the start of your turn would make this card somewhat less OP, as it would give your opponent a chance to either deal with it, or play minions to hopefully minimize the impact it will have on him. Otherwise the only decks that will be able to deal with a card like this without getting completely screwed are spell-heavy decks or charge decks.

I honestly think it’s too weak to be worth playing simply because it can’t attack. Because it’s incapable of dealing damage through attacks, your opponent can ignore it and either flood the board with weak minions in order to try and bait the effect out or merely pray that it hits the same target over and over again. It’s basically 9 mana for an infinitely recurring effect that’s only effective against big creatures and deathrattle effects, which is just too niche to find any use.
 
Basically, I’d remove the “Can’t Attack” line so it can actually affect the field outside of just sitting on the field silencing and reducing targets for an exorbitant cost.
 
@TheDeinonychus  
It’s really not as threatening an effect as you’re making it out to be. Unless your opponent has nothing but huge minions, plays them out one-by-one, and this hits them all in the right order, this is gonna do pretty much nothing.

Honestly I’d reduce the card’s health, otherwise it’ll become too much of a pain for the opponent to deal with. Silence can be hugely powerful in almost every situation, and the fact that it also reduces the target’s attack to 1 makes this a counter to pretty much anything that’s not specifically immune to minion powers.

@Vree  
Hearthstone is non-canon. This card’s lore will receive a pass.
 
But I don’t know about giving him more than 4 attack health, just for the sake of not getting removed from Shadow Words. Not gonna lie, I hate those cards so much I make nearly all of my legendaries having a four attack. I don’t know about decreasing the mana as well, due to the effect being powerful.

Wouldn’t say it fits the CHARACTER much, but an interesting Ragnaros alternative!  
Maybe a bit weak - it wouldn’t hurt it to also have att equal to health and -1 mana (tho I’d just decrease the stats a bit and make it 7 mana or somesuch) since its still leaves a usable 1/x where R. would usually just remove them. 8+ healths and big Deathrattles aren’t common enough imho to make the trade equal.