Hearthpwn

Circle of Healing with this is like mini  Dragoncaller Alanna. maybe even a Dragon Soul combo token priest looks decent.  great synergy with  Holy Nova as well as Binding Heal OH and how could i forget Divine Hymn

good stats check 

powerful effect check 

dragon synergy check 

you want this card to be overpowered?

It has taunt. You can't leave it on the board otherwise you will get smashed by 3/3s. 
Any big card is bad against aggro, you should know that already. If you play on 8 Lich king opponent just silence it and you have nothing. So it's taunt is also do nothing. Voidlord is also do nothing if gets silence so well, large amount of cards do nothing and are in top competitive play.

Takes 2 turns to set up his effect - what man? Circle of healing? Why wouldn't you put 2 circles, nortshires for a draw engine and 3/5 which converts heals into dmg? It's very good cheap AOE for aggro and as priest losing dragonfire it's gonna be used 100% (in control priests, not spitefull).

Stats are okey. And if you get at least 1 3/3s it's already great. But you generally will try to heal up 2 things with circles so I you get 2 3/3s and you have 9 health minion on 7 which takes entire turns to kill. (Voidlord is pretty hard to kill right? And it comes down just on turn earlier. btw not every card have to be voidlord power level ya know?)

Only 4.6% can see this card is really bad... shows how much the average player knows about this game

Good!

Even tough Dr. OP will be missed Dragon Priest lives on.

Really difficult to get max value imho. It's interesting, however If I want to flood the board I might just well play Onyxia. But who knows, who knows

3/3s are a lot better than 1/1s
7 mana is A LOT better than 9 mana
and it's a target which you must kill due to it's ability.

I think it's really good. Well even if you heah 2 minions and summon 2 3/3s it's pretty nice. 

Bloody dragon priest will keep haunting me again and again so it would seem.