I'm not sure about this one. I mean if the opponent has many minions, it is still lots of incoming damage, against single targets we have similar thing just for 3 mana. Also the 3/7 body for 7 mana is pretty weak. I do not say it is bad, but definitely not OP. Probably best against handlock, but against it, paladin already had the tools.
Too expensive for my taste, but I'll be damned if I didn't want to play this guy for the shear fun of making a board full of mid game minions useless. Maybe if the statline were a bit better it would be playable, but 3/7 for 7 is just terrible even with that great effect.
As with Mass Dispel, you're spending a lot of mana and not actually removing any creatures. The only matchup I can think of where this guy would be relevant is handlock, against everything else he's just a more expensive and clunky Aldor Peacekeeper.
Certainly don't see him competing with Dr. Boom in the 7 slot, and how many 7-drops are you actually willing to run in a deck that already runs expensive cards like Tirion Fordring, Lay on Hands, etc? Just don't see him fitting.