Honestly, I have to agree with Luxuria. The idea is unique and interesting, but stupidly tricky to actually try and balance. Buff its attack and it’s potentially too damaging or punishing if it sticks on board for a turn. Buff its health and it becomes too hard for your opponent to actually stick anything to the board that isn’t large enough to survive against it unless they draw into a removal spell or play multiple minions or something. It’s clearly too weak given the similarities to Cairne, but where the statline could reasonably go is nearly impossible to figure out.
 
Honestly, it’s even harder to balance because it’s an Epic. If it were a Legendary you could cut corners a little bit and hedge towards a slightly higher power level, as you’re limited to only 1 on your deck and therefore have lower odds of drawing it, but you can’t do that for Epics, Rares or Commons.
 
It’s a unique idea for sure, and I applaud you for that given how many unoriginal ideas I’ve seen, but I just can’t see it balancing out all that well.

It’s pretty hard to balance. If you make it “until your next turn” it’s too strong, and as is it’s too week. I think the effect is just sort of hard to make work.

@Marioland
 
So… what it should be in Great Tournament reality? 4/6 for 6 with such mechanic? Or be more strong and expencive?

You can’t attack with it immediately, so it’s pretty easy to kill off since it’s essentially just a Chillwind Yeti for 6 mana. If it somehow survives, you still need to attack with it enough to somehow beat the value of Cairne, which is just really unlikely.
 
Cairne hasn’t seen play in ages, and this is even weaker the turn you play it. This is just too underpowered to work.

@Luxuria Unus
 
It’s The Grand Tournament card. Yeah, I’m… not english native, so I mistaken with keyword. I think it was actual when this expansion went on. But now…

Not sure if you actually meant the keyword Inspire, or if inspiration is a custom keyword. But since you give no evidence to the contrary I’ll assume the former.  
It’s solid enough, no glaring problems. Not sure if it’d get much play, least of all right now. Warriors have enough health in their competitive decks to spare in super collider swings, which is all this’d really affect right now.
 
But looking at it outside the current meta, which all cards, custom or official should be. It could see play, and deserves no immediate write off.  
Perhaps I’m missing some shenanigans here, but it seems reasonable, and something I’d very much expect from a Blizzard card. I think not enough people value restrictive design, not every card has to be an over the top legendary. So all in all, if nothing else, I enjoy the conservative nature of this card.