Cleric- a 1-3 for 1 mana is pretty decent. But the ability requires that you normally have to spend 2 mana you might need to control the board.once a priest loses control of the board, the games probably over. And that a there is a minion to heal.
Lightspawn. a 5/5 for 4 mana is great. But it can be silenced or nuked down. It doesnt even need to be hard removed. you can nuke it, and then the priest has to spend more resouces to take it back up or close to where it was.
Lightwell- This card is so terrible that there is not much to say.
Smite- Its just not enough damage. the mana cost is great. But its hard to remove something with 2 damage.
Shadow words- all around pretty good. But there are so many 4 attack minions that it becomes incredibly frustrating that once you see a yeti, a ton of resouces must be spent to remove it. A priest can lose an entire game from a 4th turn yeti..
A. Soulpriest- Again. its dependent that you spend more resources (if it lives) to make use of its ability, and that there is something that is worth nuking, or that you have a circle of healing and are in a situation where nuking the entire board, including your minions is a good idea.
Mindgames- Again another gamble. Do I get rag or a 1/1.
Holy nova- 2 damage is not enough for 5 mana. The board has to be perfect to really make use of holy nova.
Shadow Madness- dependent on a board that you can use it on. If not its dead in your hand.
Cabal shadowpriest- again dependent on a board that you can use the minion steal. But when is there a 2 attack minion out on turn 6? if not you just spend 6 mana for a 4/5.
Inner Fire and Divine Spirit- Both are gimmicky and can win you the game. But most of the time you throw 2 or 3 cards into a minion and it gets removed or silenced and you lost.
I have tried to make a deck that works, I have access to most cards, and I have tried net decking decks online. There simply is not a way. Any deck is behind 80% of whats played out there. The way the priests cards are structured is that each game is so dependent on certain circumstances that it becomes impossible for priest to be competitive. Under rank 10 or so, there arent priests. None. Not one. I would guess that in the last 100 games ive played on ranked, that ive seen maybe 2 or 3.