Hearthpwn

what about Cairne Bloodhoof ? instead of Mojomaster Zihi? Or there will be too much deathrattle minions?

It's too greedy, which is unnecessary in the current metagame. You either die to Aggro decks like Odd Rogue or Hunter, or you get OTK'd by some sort of combo like Mecha'thun or OTK Paladin. Zihi helps against the later, and the combination of Deathrattles with Immortal Prelate and Plated Beetle means you get armor (the effect stacks, so every time Beetles dies you get more and more armor, you can get 40 armor in a turn for example, in theory).

I think Tirion Fordring would be a very good addition to this deck.

But there is a risk that Ashbringer could be replaced by Val'anyr. So it seems to be useless - unless you don't equip Val'anyr at all. IMO it's safier to have only 1 weapon from deathrattle

Which legendary should I craft first? (I have Genn)

Those suck obviously, but to completely destroy this deck then need 3 silences. Try to lure them out by buffing something that's not a Prelate.

thanks, nice deck!