Hearthstone has, to date, 10 playable classes in the game. Each and every class in Hearthstone has its own set of cards unique to that class, and most classes have entire mechanics unavailable to any other class, as well. Each class has its own strengths and weaknesses, and it's up to each player to build a deck either accentuating a class's strength or reinforcing its weaknesses.
For this list, we'll be taking a look at the Priest class; going over some of the strongest aspects of it, and some of the cards that are going to help flesh out your decks:
10 SILENCE
One of the mechanics that the Priest class can make really strong use of is Silencing minions. Silencing a minion takes away every effect that the minion has, other than it's Attack/HP. This will make a Taunt minion into any other minion, get rid of a minions Deathrattle, negate a constant effect that a minion has, etc.
Nine out of ten times you're going to be using this on an enemy minion, but every once in a while there will be a minion of your own that has a negative effect that you'll want to silence.
9 HEALING
The Priest class usually also makes heavy use of healing. There are so many cards available to the Priest that restore health to minions/your Hero that simply outlasting your opponent is a distinct possibility/strategy.
8 GALAKROND
The Priest class is one of the classes lucky enough to have access to Galakrond. For the Priest, invoking Galakrond adds a random Priest minion to your hand. The Priest class has some of the minions with the craziest effects, so this invoke-ability can really change a game.
Summoning Galakrond straight-up destroys a certain amount of enemy minions, depending on how many time's he's been invoked. This is a, quite frankly, insane board-clear, and can help you establish dominance in one fell swoop.
7 ACTIVATE THE OBELISK
Activate the Obelisk is a 1-cost Quest that requires you to restore 15 Health. Once you do, it replaces your Hero Power with Obelisk's Eye, which restores 3 Health and, if targeting a minion, gives that minion +3/+3. Allowing a Priest to activate Obelisk's Eye is a sure-fire way to make the match one-thousand times more difficult to win, and there are plenty of Priest's out there used to seeing opponents concede the moment this card is played.
6 GRAVE RUNE
A 4-cost spell, Grave Rune gives a minion the Deathrattle: Summon 2 copies of this. This can really, really create a frustrating scenario for your opponent when placed on the right minion. Putting this on a Convincing Infiltrator (which we'll get into shortly), for instance, is one of the most irritating things you could possibly do.
5 PSYCHOPOMP
Psychopomp is a 4-cost, 3/1 minion that has a Battlecry that brings a random friendly minion that died this game back from the dead, while also giving it reborn. In order to make good use of this, you either have to be the luckiest person on this planet or else plan ahead. If you've only got a pool of one or two minions that have died this game, you can be reasonably sure of what minion this is going to bring back. And if you bring back the right minion, this can go a long way in ending the match in your favor.
4 CONVINCING INFILTRATOR
And here it is. Possibly the most frustrating minion to encounter in the entire game, not just because of what this minion can do, but because of what kinds of decks can be built around making heavy use of it.
The Convincing Infiltrator is a 5-cost, 2/5 minion that has Taunt and a Deathrattle that destroys a random enemy minion. At face value, this might seem irritating but not infuriating, but when a deck is built around bringing minions back from the dead, you'd better get used to seeing this minion. Repeatedly. Over. And over.
3 SANDHOOF WATERBEARER
The Sandhoof Waterbearer is a pretty strong card that you can rest assured you're always going to get at least some kind of value out of. This is a 5-cost, 5/5 minion that, at the end of your turn, restores 5 Health to a random damaged friendly character, be it a minion or your Hero. The enemy is going to have to deal with this minion fast unless they want the situation to spiral out of control.
2 CATRINA MUERTE
Catrina Muerte is an 8-cost, 6/8 minion that, at the end of your turn, summons a friendly minion that died this game. Again, with smart use, this is likely going to bring back another convincing infiltrator, so dealing with this minion with some serious swiftness is paramount. Unless you'd just like to hit the concede button right away. Which is, like, always an option.
1 MASS RESURRECTION
Mass Ressurection does exactly what it sounds like it does. At the price of 9-Mana, this spell summons 3 friendly minions that died this game. This is, in all likelihood, going to once again bring back a cursed Convincing Infiltrator, and if you're lucky, could also bring back a Catrina Muerte just for her to, at the end of the turn, summon yet another Convincing Infiltrator.
Seeing the pattern, here?