Normally mechanics that occur on your next turn are garbage, but in this case he has enough health to almost guarantee surviving to the next turn. Either that or your opponent has to waste hard removal to remove a not so threatening body. Either way is a good outcome.

Update: Ben Brode has clarified that it's at the start of the GAME. He mis-spoke during the live presentation :P

Quote from 0xrgb >>

I'm korean and I think card text is wrong.

In Korean, the card says "At the start of game~". So you could start game with 35(30 + 5 legendary) cards.

This card is like.... Golden Monkey. 

Wins Fatigue wars in control vs. control match ups, but aggro decks will not even care.

The effect is interesting and unique at least, so good Legendary!

Edit : Now that we know it is at the start of the GAME that the cards are added, this card is worse. 5 random legendaries could be anything. If I'm playing mage, I sure as hell don't want a random Flame Leviathan (in wild) to pop out of nowhere, without me being able to expect it at the slightest.

It will lower your chances to win vs. Aggro, because most Legendaries are high-costed cards (and the cheaper ones are all pretty much ignorable for aggro decks) and don't forget that a lot of Legendaries are highly situational or just bad!

Quote from Destruction3402 >>

First neutral demon, or am I missing something?

Old review
This card is… Ok. 
a. Upsides: Gives probable late-game options to anti-aggro designed control deck. 
b. Decent stats.
c. 35+ cards deck, very good in fatigue match-ups.

Downsides:
a. Many added Legendaries could be dead draws (Lorewalker Cho, Nat Pagle…)
b. Its efficiency also relies on the class legendaries you're playing, and even if the class has good legendaries, the class may not have an archetype where it fits.
For example, I like it a lot in Rogue for instance, but I don't see any rogue deck where the card could be useful.
c. [Maybe] As I see it, if you put Tirion in your deck-list, you won't be able to get another one through this card. Therefore, this card is better for classes that have decent/good legendaries but not good enough to be played as a must (e.g.Rhonin, Confessor Paletress…) 
IF this card only considers the remaining cards in the deck, then forget about this part.
d. And of course… It's not a Battlecry. It could be more than 5, but it could also be 0. And getting a vanilla 5/6 for 5 in constructed is sad.


OOPS.

I made this review and this information went out: 

BEN BRODE: Malchezaar's trigger is "At the start of the GAME", not start of turn. It triggers while its in your deck.

Thanks for tuning in! Excited to talk more about Karazhan and address everyone's questions once I get back from my trip. On to Australia!

New card review

Prince Malchezaar
My opinion: ??? 
Pretty bad, right? It's the F2P dream but as a competitive card, well…
It makes your draws uncertain and makes the deck less consistent. 
Nobody wants that. Aggro does not want to draw a 10 mana legendary on turn 3, control also does not want to draw this instead of his solution such as Brawl or Entomb. You never want to draw a Milhouse Manastorm or Lorewalker Cho (even a King Mukla) instead of one of your normal cards…
Legendaries are either heavy cards or pretty bad cards.
I know Elise Starseeker is a good card contrarily to what many thought at first sight, but now i don't see this being playable right now. Late-game solutions with the Old gods, Starseeker and even cards like Ysera are simply way better.
Oh, and also, it takes one of your cardslots for a 5mana5/6. 
However, we shouldn't forget that the deck becomes a 35 cards deck… 

Looking at the comments here, looks like i'm the only one thinking it's trash and that i'll have a good time playing against people drawing shitcards instead of their swipes and brawls… MingLee

I call it right now: this card is not a tool for control. It's BAD, a hit, for control decks. You know why? Because it's bad against aggro BUT we will have guys thinking it's good and fun that will run it. And what will happen when you'll face them with a well-built control deck? You'll lose to fatigue, diminishing your winrate. Therefore, you'll either include it in your deck or you'll switch as almost everyone now to tempo/aggro decks. 

Turns out it is preeeeeety good

Ok, this changes everything. It's a vanilla 5/6 on 5, gives you 5 random legendaries at the beginning of the game... staple for control warrior and priest.

I'd say this is better than the monkey in a fatigue game since the monkey doesn't give you cards it just swaps your existing cards with legendaries, whilst this on the other hand gives you 5 new legendaries that prevent fatigue and you keep all your valuable removals/heals you might have lost after playing the monkey. :)

Yep!

It seems that the effect will trigger at the beginning of the match if this card it's in your deck. Quite impressive if I may say...

Quote from Hejnewar >>

Even if he shuffles 5 random cards it will be pretty OP in control vs control when comes to fatigue. In other matchups is not that good.

Quote from 0xrgb >>

I'm korean and I think card text is wrong.

In Korean, the card says "At the start of game~". So you could start game with 35(30 + 5 legendary) cards.

Yes. You can have effect when the match starts.

Mill rogue now gives a 6 card advantage with Gang Up + this card and your opponent draws aswell maybe comeback of mill rogue?

Holy shit they just love Reno decks this expansion, but seriously this is like incredible for a fatigue warrior. It adds so much power o a deck so often. I wonder if you get to see what you add. Because it takes place at the beginning of the game, also does it have a class occurrence boost if so it is even better.

Quote from SampexD >>

I'd say this is better than the monkey in a fatigue game since the monkey doesn't give you cards it just swaps your existing cards with legendaries, whilst this on the other hand gives you 5 new legendaries that prevent fatigue and you keep all your valuable removals/heals you might have lost after playing the monkey. :)

If it's at the start of the game I think the card is bad/very situational/meta dependent. You don't want 35 cards in your deck in almost any matches, since it lowers the chance of you drawing what you need. Especially in your starting hand and the first couple of turns. We all know how important it is to get FWA, Pyro/Equality, SW: Pain etc. turn 2. 

And also it doens't fix Mill Rogue as I thought, since it still makes it equally difficult to find Coldeye even if you put a similar amount of draw into the deck

Alright, this should be the final update to the card text until the official English card comes out. Thanks, and have a good night!

Can't wait to test this card in control warrior.