Hearthpwn

It took a lot of tweaks to get this deck right, but boy does it deliver.

It's not an easy deck to play, so don't expect easy wins, but if you play it well it's an awesome deck to play.

First let's talk about gifts:

The general rule of thumb is to try to get as much value out of each gift. It's not getting the most gifts that will win you the game (though arguably it helps), but it's to make each gift count more than your opponent's.

Prophet Velen Probably the best gift in the game. It can serve as a get out of jail free card, or as a win condition. The difficulty is to chose the right timing to play him out. He provides insane damage burst. I've ended some of my games with double Velen, holy fire, holy fire. It's especially good against druids who can give you Starfire too.

Entomb Awesome tempo card to either remove a threat, or to make use of your opponent's tools like Void Terror Crazed Alchemist and similar. Very versatile, I've never regretted choosing this one.

Holy Fire Be very conservative of your holy fires. It's tempting to kill a gift with it, but its awesomeness is revealed once you have Velen. Obviously it's one of the hard decisions you'll have to make: to keep or not to keep.

hard packed snowball Great tempo card. It's worth noting that some classes tend to end up with tons of cards in their hands. The snowball can fill it up pretty quickly. Favor this card if your opponent has expensive minions out. Be very careful not to return gift enablers like Void Terror and Crazed Alchemist.

Holy Nova Holy nova is situational, most of the time you'll get better picks. However if you already have a Velen in hand, it becomes a very solid option. If the other picks are not great, you may want to opt for it, and keep it warm in your hand while you wait for a Velen. 

Lightbomb This pick is also rather situational. Most of the time it won't clear the board effectively.

Confessor Paletress I generally don't like random things, and Confessor Paletress is no exception to this. She just won't reliably deliver. But sometimes she's just the better pick.

Mind Control At 5 mana you'll be giving away a lot of tempo. I usually keep these only against warrior, to steal an enraged grommash. As good as it looks, it's generally not a great card choice.

Excavated Evil just one damage short of killing the gift, and you'll feed your opponent cards. I only chose it if it allows me to clear the board, or if I'm playing against a warrior (to enrage Grommash if I ever get him)

[Vol'jin], [Cabal Shadow Priest], and temple enforcer sometimes come in handy. They all are very situational most of the time though.

Upgraded Repair Bot this card is just garbage, never pick it.

How to play

You have lots of tech to kill your gift, or your opponent's. Keep in mind that if you have the choice between killing your gift, or your opponent's, always choose to kill yours. During his turn, he'll only have 1 gift to kill, and it's much harder to kill your own gift. Moreover, you really shouldn't let your opponent get his hands on a Prophet Velen.

You'll almost always start with a cool early game option.

Besides the obviousconfusion, Crazed Alchemist and Shadow Word: Pain you have a few other options inDoomsayer or Youthful Brewmaster, which you should always use on your gift, or to save your Auchenai Soulpriest.

The Auchenai Soulpriest and Circle of Healing work extremely well, not only because it kills all gifts on the table, but also because most decks don't run creatures with more than 4 hp. If you returned a gift to your hand, make sure you play them out before doing the combo. You'll win a lot of games when your opponent rage quits after you drew 4 gifts in a single turn.

Loatheb Is insanely good. Especially against Druid, which will most of the time win with sick savage roar combos. It's important to get the timing right. Try to keep track of how many gifts your opponent has. If you manage to flood the board and play Loatheb, chances are he won't be able to clear.

Lance Carrier This card I'm still pondering. I can't say I'm never happy to have it, but sometimes it's just a dead card. Abusive Sergent is most of the time just as good. I'm thinking perhaps of trying to replace it with a mind blast though, to better support the Velen win condition, or with Flash Heal, which offers some versatility too, with Auchenai Soulpriest

Thoughtstealand Mind Vision I found the deck needed some draw, because sometimes the right cards just won't come. But given how the boards are wiped very consistently almost every turn in those games, neither Northshire Cleric or Acolyte of Pain seemed to cut it. However Mind Vision allows you to have a glimpse at your opponent's hand, and if you keep track of gifts, you can use it at an appropriate timing to get yourself a free gift. It will also sometimes steal a void terror or an acolyte of pain, or some other tech your opponent has.

Mulligan

You should always have a solid turn 2 play. The best conceivable starting hand would be to go second and have Youthful Brewmaster,confusion, Crazed Alchemist, shadow word: pain

If you get aDoomsayer, keep it. It's usually safer to play him early. I rather have my opponent waste a crazed alchemist on my doomsayer, rather than let him have an easy gift early on.

If you have the soulpriest/circle combo in hand, keep it if you have a turn 2 play.

Modifications:

-2 Lance Carrier +2Convert  (convert is awesome, really awesome)
-2 Mind Vision +2 Flash Heal (more flexibility, and possible lethal with velen/soulpries combo)

that's it, enjoy this deck