Hearthpwn

The Shaman matchup just isn't that good I believe. 

I've played this deck with no Thalnos, I've just run more neutral draw. You can also just play extra AOE or removal. I would recommend something like Excavated Evil just for cleaner board clears.

In order to do the 30 damage with Malygos, you need to get more than one Thaurissan discount on one mind blast, usually. For the combo to work, Velen doesn't even have to be in your hand, most of the time.

Talking about adding more cards meaning that per your usual draw, you are less likely to draw Reno. It's not about getting the actual effect off, its about drawing Reno in time to tempo swing against aggro. 

All depends on what kind of decks you want to play. Sylvannas Windrunner and Ragnaros the Firelord are pretty sizable threats in both Midrange and Control, even some Aggro decks might play Rag at the top end. Justicar is a decent choice if you really want to play heavy control style decks, such as N'Zoth Paladin, Control/C'Thun Warrior, Control Shaman, and some variants of Control Priest. To answer your question specifically, Justicar is mainly for decks looking to play an extremely long game and is more niche than other legendaries listed here. 

Unfortunately, Priest is the worst class in the game right now. While you can tech to beat Midrange Shaman specifically, you need to draw Auchenai/Circle on curve and have excavated evil as a follow up. Even after that point, you're still slightly unfavored to win the game. And that's if you've prepared specifically to beat Shaman. The prevalence of Malygos Druid and Tempo Mage on ladder make Control Priest just an abysmal choice for laddering up. Even though Res Priest can win a few games here and there, too many heavily unfavored matchups exist in the game currently. 

Shoutout to Fr0zen for even bringing this to Last Call.

As a fellow priest player, it's upsetting to see the best class in the game currently have a cheap answer to your blademaster, then play a zero mana  5/5 taunt. However, I don't see that particular effect being useful in the way that Hex is. Blizzard should not make cards to simply counter one strategy and strong-arm an archetype into the meta game. If the card does not counter deathrattle effects, then what use is it really? I think more neutering effects in the game should be implemented instead, something similar to Aldor Peacekeeper. I do indeed share your sentiment that Priest need a more consistent mechanic then high rolling your dead blademaster, but I don't see changing Transformation effects in order to cater to Priest being the answer either. 

Greetings, Traveller

I actually really like your deck list, and am playing something similar myself. My question is this: what is your answer to extremely greedy decks? I had a situation last night vs. Reno-Malchezaar Warlock where I lost a joust five times to Skeleton Knight, and only lost when he Shadowflame-Sylvannas to steal my Cairne. I am running Elise, but I'm pretty sure Malchezaar just makes your matchup vs. aggro absolutely abysmal. Any other suggestions? 

Congratulations good sir. Any reason you decided against aggro Shaman for your laddering, or a version of Tempo Warrior?

Ragnaros. You're almost guaranteed to kill one minion, or remove a third of your opponent's life total. If it puts them close to lethal, they have to remove it immediately, and unless they're playing one of the more controlling classes, a heavy amount of resources must be invested in order to remove.