Hearthpwn

Think about this in a zoo deck, on curve.  4 mana 5/6, and it forces them to play a minion on turn 4 or 5 instead of dealing with your board full of dudes with a spell.  That means your board stays AND you have another token.

If I recall the stream correctly, this was played in the Druid token deck, and I think I see why.  If you are ahead on the board, this makes it really awkward on the opponent to deal with your board AND this minion.  As the opponent, you can put out a bad minion, which then means you are getting stomped next turn because you haven't dealt with the board.  You can put out a good minion, which means the opponent also gets a good minion.  Or you deal with the board with a spell, and then you have to deal with a 5/X, that has to be killed with a spell the NEXT turn also, or else it again will turn into a minion.

I dunno, this one could see play.  Not saying it will, but it could work in an aggro deck.

Why this is not a common or rare ? 

So situational it became dust.

So, this will be one of the three legendaries I open in my 80 packs...

Mecha'thun is not a good card, but it's one you want to make work at least once. Not a card worth keeping around, but fun to try out.

This is just straight up terrible. Easily the worst legendary in the entire set and one of the worst in recent history, almost Moorabi level. Even Secret Mage wouldn't bother with a 0 to 3 cost Mirror Entity, why would any other class run it for 4? And the reason why Mage doesn't use it, is because most decks out there have multiple 1-drops. It is super easy to play around, and almost never worth it.

But Celestia isn't even a Secret. Your opponent knows exactly when you played her and what she does. There is not even a chance he would accidentally play into it. So at the very best, this card can slow your opponent down for a turn or two, forcing him to look for a cheap minion. But even that is an optimistic guess for a card, that is surrounded in a meta full of Fire Flys, Kobold Librarians, Glacial Shards and Dire Moles.

I rarely ever say this, but this is a card I would consider disenchanting right away, if it wasn't for the chance I could get a second one.

Mirror Entity is better, as it could be any of a few secrets and may result in it actually copying something big. This one they know exactly what it does and can just play around it.

I was looking forward to seeing the last neutral legendary of the set too :(  Really struggling to see how to put this to any use. 

My free legendary, I'm calling it now.

this is the card you get golden with pre order...

Here is the most trash legendary in the expansion 

Its slow... has potential but can be REAL easy to play around... just bad... probably dustable 

I hate this card I know I'm going to open in my first 10

I think this it's an okay to decent card, depending on the meta. If you play against aggro, obviously it's horrible. But still, it forces your opponent to consider this as either a Mirror Entity or a a Potion of Polymorph  either you play into Mirror Entity and give your opponent a strong minion, or you counter the effect by playing something small, but forces you to play your cards suboptimally. Not acting is not an option though, as leaving the 5/6 up for a turn is definitely a shortcut to losing board control, since it will still transform when you play your next minion.

Great design, hope this will see some play, as aggro decks have always been quite frequent, I don't have high hopes.

Behold: the legendary equivalent of a magma rager.

I'm super salty about the wasted name and art here. This is a 4-mana Mirror Entity that's not actually a secret, even. No element of surprise here.
At least make it a 10\10. Don't have a minion to play? OH, WELL THAT'S A SHAME THEN, ISN'T IT? The whole "harbinger" part becomes very real.... oh well...

It would have been a really neat card if it kept the ability between the transformations, so that it would always be the minion your opponent played last. Maybe you'd have to ditch the stealth then, but it would be really cool!

I personally want to see how long it takes for a Trolden video to pop up, where the opponent plays a Doomsayer as a blatant "Fuck You!" to the guy using this card. Play Doomsayer, end your turn, then revel in your opponent's delicious salty tears as he ragequits.

Awful

Worse than Mirror Entity

Quote from Tasidul >>

This is like, exclusively anti big-priest tech. Play it against any control deck and they can just turn it into a raven familiar or worse (doomsayer); play it against aggro and they turn it into a fire fly. The funniest part is that it's SO good against big priest (and incidentally no minion hunter) that it might see play in wild.

 It's when they play a minion not summon so good chance this becomes Barnes against big priest. Good if it stays itself and they don't have Barnes to play into it.

Pretty terrible.. only really good against big priest or Maaaaaaybe big Druid..