Hearthpwn

Dont play it if you feel like you can win without him, it can lose you the game. It happened to me once, Control Warrior had 3 hp, I was at 18. I thought that it would be fun to play the card and see what happens. I had no cards left btw, so that bastard used Lay on Hands andSprint. We tied :(

I've played him 4 times now and he always worked to my favor. I really love him. I climbed from rank 8 to rank 7 with a Yogg deck and then felt down to 8 again with a Renounce Darkness deck.

I've been using  a controlish/miracle rogue for yogg-saron (usually end up winning but yogg because I dont play to win) and most of the time he kills the entire board. I'd suggest trying it if you want, there's many ways to get brann and yogg at the same time

For me personally (around 10-12 games where I pull him off):

Yogg almost always draws like crazy.
Yogg almost always boardwipes, whether it be through direct damage spells, or by boardwipe spells
Yogg almost always plays secrets (and most of the time, it's useful eg spellbender, counterspell)

My suggestion is to always puke out your hand before yogging, because from my experience you always get flooded hand wise.

Attached a photo as an example - not a particularly good pic, but  I won that game because of him.

Yogg has been awesome so far. So many amazing games from him. He's actually caused some of the most amazing moments I've ever had playing this game, and I've been playing for a long time now. This card is 10/10 on the fun ss cale, but probably pretty bad for competitive, not because it's bad, but because it's u predictability. If you're in it for the laughs and the most epic hearthstone moments, this guy is your guy. 

YOYO- You only Yogg once 

The reason this isn't on my crafting list is that "random targets" makes me think he'll hit me, too.

Despite all the "this is so much fun!" posts I've seen, I'm still not sure it's worth it to have a card that can potentially kick your own ass. (At least Injured Blademaster can be backed up by Circle of Healing!)

I don't own yogg but one time i had the best RNG with him.

Losing to rogue, fandral druid.
shifter zerus in hand. becomes yogg.
Yogg does a bunch of spells, I end up on 11, 14 for them, yogg is only guy on board, i have effigy now.
they kill Yogg, i get sea giant. they cant play a taunt or kill it more. they hit me with something to my face.
druid of claw in hand, pull a raven idol, go for spell, get new feral thing for +4 attack. 
16 dmg to face, winning game.

to recap: Zerus>Yogg>effigy>C-giant>raven idol>Feral thing>DoC=lethal.

It's good. If you're looking to play the best decks, dont craft it. If you are considering having fun in an online card game, I haven't regretted the craft one bit. 

Thanks to getting Cabalist's Tome from Cabalist's Tome three times, I casted 22 spells... plus Brann Bronzebeard being on the board. 44 damn spells...

Sylvanas stole my Yogg, but it ended up backfiring and casting renounce darkness on my opponent then killing my opponent XD

Yeah, he's a Hail Mary card for me, I use him in this Miracle Rogue deck like a lottery ticket in case everything else has gone wrong. Sometimes he'll bring me back from an otherwise un-winnable situation. I never, ever play him when I'm ahead though... way too unpredictable.

i am still wondering i should craft this card, or maybe save the dust for something else? 

just watched the game posted by kibler, it does look like a very fun card to play with. decisions decisions 

I have seen it being played it's mostly beneficial for the user, and sometimes does nothing or harm you too RNG for my taste tbh if you play a 10 mana card you want to be benefitted from it mostly..

Aggro Yogg Hunter:

1) Summon Yogg-Saron, Hope's End, takes me to fatigue and 10 health

2) Gang Up casted on Yogg-Saron, Hope's End.

3) Tree of Life casted - back to full health

4) I basically have a Secret Christmas Tree and end up playing Yogg-Saron, Hope's End 2 more times.

Still lost, but worth the lost.

tl;dr if you call it a win more card you're using it horribly.

Who ever came out with the idea of Yogg's random spell should be sacked.

One time it took full 3 minutes to cast ALL the spells......

i crafted it and played my first game with it. 

played him and he won me the game against a midrange shaman. most importantly, it was FUN!

This card is amazingly fun but I am not still on the edge about its usefulness. I have played it a few times now the first time I played it, it almost stopped my win the next turn. It's killed me twice and all round hasn't actually contributed allot to the fight as it usually destroys the minions it makes. It is good at drawing cards though :D

This card is incredibly fun to play though like seriously, I just wouldn't consider it being all to competitive but that's really just RNG in general.

Usually I play Yogg for fun when I'm really ahead in the game, or when I'm in a bad spot. I lost games by playing Yogg, but those games were lost anyway. But it saved me games so often. I just won against a C'thun priest thanks to Yogg. I was in a bad spot, I had to survive to his C'thun on board since 2 turns, and my C'thun and blade of c'thun were in my last card, so no hard removal. I had vek'lor twins to protect me at first, and then, nothing on my board, against his 17/14 C'thun. Still no blade of c'thun, or c'thun himself. So I went for Yogg : sprint, got me both C'thun and blade of c'thun, and then he casted Misdirection :D casted some spells to the priest face, 8 health left for him, 12 for me. He went face with C'thun and..  well, you know the end of the story. So yeah, he's good. 

In casual I play him all over the place though. I'm just curious to see what happens

I've noticed the following trends:

He tends to stack secrets on your hero, rarely if ever on the opponent. 

He tends to kill off the board almost always

He tends to force draws on both players.

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I wouldn't play him close to fatigue. 

He's being pretty good to me. I'm playing him in the tempo mage deck. 6W - 2L. He's been good to me 4 times, 2 times meh, 1 time bad, 1 time didn't get to play him because I was dead by turn 6 to zoo.