theres a video on it on battle.net go watch it it pretty much explains it. 
you discover 3 different times
first time is cost 1 5 or 10 
10 is picked in the video

Second time is first spell effect: 
Options for 10 mana are: 
Powerful mojo > add three cards from your opponent's deck to your hand
Felbloom >  deal 6 damage to all minons
Kingsblood > Draw 3 cards

Felbloom is picked in the video

third Discover is the second effect:
Options for the 10 mana are: 
Ichor of Undeath > resummon 3 friendly minions that died this game
Stonescale Oil > gain 10 armor
Mystic Wool > Transform all minions into 1/1 sheep

Ichor of Undead is chosen in the video.

So your options for 10 mana are: 
Board clear + Resummon
Board clear + Armor
Board Clear + Sheep (which is useless)

Add 3 cards from opponent's deck to hand + Resummon
Add 3 cards from opponent's deck to hand + Armor
Add 3 cards from opponent's deck to hand + Sheep

Draw 3 cards from your deck + Resummon
Draw 3 cards from your deck + Armor
Draw 3 cards from your deck + Sheep

Depending on when you play him in the match will greatly decide what is useful for you. 
the 10 mana Board clear means nothing if you're ahead all game. 
the 10 mana draw 3 means little if you're in a top deck mode and behind (delays you 1 turn from playing any draws and allows you're opponent to farther their lead.) 
the 10 mana copy 3 cards means a gamble if you're in a top deck mode. (stealing 3 copies of 2 or less drops from you're opponent doesn't help if he can clear them as fast as you play them.
the 10 mana Resummon can help to regain tempo but you risk paying 10 mana for say 6 mana worth of minions. (3 2 mana costs)
the 10 mana armor isn't incredibly useful unless you're trying to push another turn (if you're behind, it could say one turn, if you're ahead there was little reason to pick it to begin with.) 
the 10 mana Sheep is useful if you're opponent is playing a synergy style deck (bascially if you're opponent is playing anything that brings cards back N'zoth, Anyfin...etc or anything that buffs similar Pirates, Murlocs, Or has a lot of stronger than 6 health minions (because you can combo it with the deal 6 to all.) 

A couple of things to note.
1) the spell maybe a bit more random. there is nothing stating that these 6 options only appear on their stages on the video. 
meaning: It maybe possible to pick Sheep + Resummon because it might pick 3 effects from a list of say 8 (with 2 unrevealed) and then pick 3 effects from the remaining 5 (meaning that you may have games where he doesn't give you the option of Felbloom.) 
2) the Spell will activate in the order the effects are listed. Meaning Felbloom + Sheep would deal 6 damage to all minions AND then transform all surviving minions into sheep 
3) the mana cost options may also be from a list of more than just 1 5 or 10. (though it seems like that's unlikely. since 1 would be asking for a quick spell, 5 would be asking for a midgame spell, and 10 would be a major spell) 

I hypothesis that all mana cost versions will be just weaker versions of the other options.
Meaning that a 1 mana cost would probably give you options like: 
Felbloom > deal 1 to all minions
Powerful Mojo > Steal 1 card
Kingsblood > Draw 1 card
Ichor > resummon 1 
Oil > 2 armor 
Wool > Polymorph 1 minion 

this would still make an overpowered spell (which any 1 mana cost spell with 2 effects would be anyways.) 

Its possible that 1 mana cost spells will also have Negative effects like take 2 damage in addition to the other effects. but hey this is just a theory...a game theory.

in spring. You'll still have 3 months to play with him with this card before he goes bye bye

probably just them adjusting it for size. Karakus uses 25 letters (without spaces) Reno uses 39 (without spaces) for the same meaning. 
Honestly i wager it'll become a named mechanic like Battlecry, Taunt, Enrage...etc  assuming that there is enough cards that perform that function. 

wording wise, i believe it would work identical to reno. Since at the time of playing if you drew all duplicates the cards remaining in your deck would be all single copies. Your current deck would not have any duplicates. On the reverse spectrum. if its based on your deck at the start of the game it means you can use gang up and it at the same time and have 4 uses from it.. 
honestly i think the wording was just revised to fit better. 

Reno's text was designed with him being an Experiment. At the time of creation they did not know if they were going to ever do a similar effect. So they used the most clear text they could. This was proven back when they had to add in something they didn't plan on: 
Making him glow when activated. 

For them to keep creating cards like this they have to limit it's text 
Reno Jackson's version takes 38 characters not counting spaces. 
Kazakus takes 25 without spaces. which means they can add better effects 

Reno's card uses almost all the space that they can on a single card. (they can't afford to reduce the font size due to mobile play limiting how small it can be, can't make the cards bigger due to limits on hand size visuals.)

I honestly wouldn't doubt that if cards like this keep coming up, that they'll start doing card updates and retrofitting old cards. 
For example making the text:
Battlecry: reveal a minion in each deck, if yours costs more than: do X into saying Joust: Do X
Reno or Karakus could say: Singleton: Do X (singleton being the name of having a deck consisting of only one copy in Magic the Gathering) 
When this card dies: Do X ----->>>> Deathrattle (i included this one mainly because it is an effect that they named.)

Pretty much any effect that'll be reoccurring enough times will get named, and when they do name it, they'll most likely patch old cards with the name : 
making Tusskarr Jouster into Joust: Restore 7 health. or even potentially: Battlecry: Joust: Restore 7 health 

The only reason i think they didn't name Joust was because it counts as a battlecry so they have to include both words on the card which looks silly.

beneath will be there until spring. so it'll make a common appearence if players find a way to make reno decks more competitive.. Right now mage seems like the best fit, since you can use Discover and spell generating cards to fill in duplicate slots (babbling book, cabalist tome

i believe that it'll work like reno in the sense that once you draw all duplicates it'll activate. Because at that time you would have a deck without any duplicates. (they're in your hand not your deck)

looks to me like it is a revise so that the text takes less space. probably functions the same (activates if you draw all duplicates)

120:  preorder + 50 in gold + freebies. + disenchanting all wild cards for additional dust and disenchanting nerf'd cards putting me at around 10K dust. 

Imagine this: You hold him in hand and when you're opponent is one turn from winning you get the perfect card. 

for instance: 
in wild going up against a mage who has ice block out, and this turning into Kezan Mystic allowing you to steal the ice block

It turning into a Bomb Lobber when your opponent has a strong minion at 4 or less health that you need removed out alone

turning into a BGH (assuming current bgh not Post Nerf bgh) when your opponent gets the 30/30 out. 

this card would be an amazing tech card for a meta where there are too many tech cards to include them all. That's what you'll want out of it. For it to change into the 3rd version of a tech card you've already used. For it to give you a taunt when you're in top deck wars and desperately need it. This card is essentially going to sit in your hand all game, most games. Changing into random minions, some games it'll be a game changer, others it'll be a decent body for when you just don't have an answer. Imagine getting it to change into that last piece of your combo when you need it. Sure, it won't be amazing most games Often times it'll just be played as another body, other times it'll be that mukla champion that you didn't put in, but find yourself at 1 damage from lethal. 

My question though is: If it changes into C'thun and i play a card that buffs c'thun will it receive the buff and will it keep the buff when it changes again. Hell, farther more If i play mistcaller (for one of my joke decks) will it lose the buff when it changes?

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Raine_Live

Raine_Live

Here's taking a chance. Only a 1/5000 chance of winning but here's to trying. This will be the last contest i enter

Twitch ID is Raine_Live. 
I'm a new streamer who's eagerly waiting for the open beta (or a beta invite) to stream this game.