Hearthpwn

This is a fairly classic list, with a few minor modifications.
The structure of the deck is the one you see lately, with the removal of some cards that I consider unnecessary (at least until legend) and the addition of more minions that can put pressure on the opponent.

The nerf of Hysteria in fact involved the removal of Kazakus from the priest lists that brought more pressure (the one I played had also Primordial protector), so this list tries to bring the same gameplan for a priest a little more proactive.

Against aggro/burst the substantial amount of heal should be enough to win you over (7-0 against Hunter for example), along with the numerous removals.

Against midrange and other controls the value generation should be enough to make you win (e.g. 3-0 against warrior).

Obviously Lock remains the worst matchup (1-2), but with a bit of luck and optimal resource management you can win. (At least it should be easier than the priest lists you otherwise see).

Mage if it starts strong is likely to be advantaged.
__________

If you encounter DH OTK, token druid or miracle priest, Illucia is a great addition to the deck.

Against token druid even condemnation can be added.

The list is adapted to my style of play, so if you feel that the deck has too many defensive cards or too many value cards you can modify it as you like, better one card at a time.

If you want a mulligan/discover/gameplan guide for MU I can do it, if I see that it is required or the list is liked, as well as other replacements/tech.
___
Please normally don't keep Setek, draconic studies or Palm reading at mulligan.

 

Edit: Mulligan's guide:

Personally, I don't play with a fixed mulligan in my head, but I try to anticipate what my opponent may play and evaluate from time to time what my cards may be useful in.
So in the following I won't list the mulligans for every single matchup, but I will start from the cards to illustrate the reasoning behind the mulligan. As you play the deck the rationale behind each choice will become clearer, so my first piece of advice is as follows:
be flexible and don't follow the directions I will provide to the letter.

There are a few cards to always look for, and these are Wandmaker and Venomous Scorpid.
These cards allow you to put presence on the board and generate value in your hand. Against aggro they allow you to contest the board and save yourself some damage, against control they allow you to take initiative and fill your hand, against midrange decks they allow you to slow down your opponent's aggression.

If you have these two cards, Raise Deadis an instant keep (even against aggro, often these two servants compensate for the damage taken both with spells and thanks to their body).

Raise Dead can also be kept with just aVenomous Scorpid. (In this case you can also keep Setek, to be played in tempo at t2)

Desperate Prayer can be kept against Hunter or Mage if you have servants to play, or more generally against any board-centric deck if you have Xyrellain hand.

I keep Draconic Studies only against warlock and only if I already have at least one servant to play in the first 3 turns.

I keep Holy Smite only if I have targets in the first turns, in that case I can also keep Setek.

Devouring Plague is another important card, against aggro/face it is absolutely to keep. In that case you can keep at mulligan also a Flesh Giant to close the game at t5.

Hysteriais also a good keep against aggro/boardcentric decks, but I generally prefer to contest the first few turns with the board, so in the absence of minions I rarely keep hysteria: eventually I try to keep just that to find pieces to play on the board in the very first few turns.

These are basically my mulligan tips, but as I say above try to stay flexible. For example if at mulligan you have 2x Devouring Plague, Flesh Giant and Palm Reading you can keep your whole hand, so you know you do t3 Palm Reading and t4 2x devouring plague and giant. Or again if you are up against druid (token) you can keep card-generator at mulligan to try to find cards you need but can't find in the deck. (aka AOE, including Shadow Word: Ruin)
Also, many cards are flexible and usable from the first few turns, so hard mulligans rarely get punished.