I would like to see Mind Control become:
Gain control of target creature.
Mind controls mana cost is increased by the casting cost of the targeted creature.
(obvi reword as you see fit).
This means you can use it throughout the game, you dont need to get '8 mana worth' to make it worthwhile. It also means you arent going to lose your 9 cost ysera unless they coin into it.
The costs above may be out a bit, but I think its worth consideration.
The purpose of mind control is to be strong against high cost creatures, its design is to make high cost creatures weaker, which is what makes it not a really great spell, since pretty much every strong deck don't utilize a lot of high cost minions. There is nothing wrong with mind control taking an ysera, that is one of the few times it actually gets to be really good.
Having to build your deck entirely around one class is the definition of over powered.
All the cards the priests can kill things with that are class only:
Shadow Word: Pain x2
Shadow Word: Death x2
Holy Nova x2
Holy fire x2
Other priest cards that are forms of elimination include:
Cabal Shadow Priest x2
Shadow Madness x2
Auchenai Soulpriest x2
Granted, the latter aren't often used, this leaves you with ALL your weaker creatures more than likely dead, while they are capable of healing their own and when you finally drudge through all those spells, MIND CONTROL
Priests are just far too well rounded. They keep their creatures on the board, wipe your and when all else fails they just take your best cards. Having to play the whole game after turn 7-8 as if they have an MC in their hand typically means losing.
The gap between both Shadow Words needs to be increased and I honestly think making Mind Control cost less, but be a one turn control of any minion that you can use ON THAT TURN is completely fair.
How close do other classes come to a priest's in ability to kill stuff? I mean, they are priests and they give rogues a run for their money on the subject of murder. Where is the thematic sense in that?
The sad thing, for priests that is, is that a deck which is good against priest, is a good deck in general.
Every one of my strong decks are currently good against priest, and not in any of them was I thinking about countering priest, it just happens to be that what makes a strong deck, also makes a deck good against priests.
And on the other side of things, bad decks are punished greatly by priest, if there comes a tournament with thousands of participants I'll probably run priest for the first 5 rounds or something to get through the trash, but after that I would need to switch it to something better.
Priests also lack severly in AoE, they have only holy nova for that, people should be abusing this, but oh wait they only have high cost minions so they can't afford to put more than one out at a time for the first 7 turns.
If people also run less creatures with less than 3 health they will drasticly reduce the effectiveness of priests only AoE, holy nova, and make shadow madness far far less useful.