I and I'm sure many other people have thought about a card like this existing. But it existing is an extremely huge problem and at 5 mana. Honestly a card like this should be at the least 9, even 10 mana to not be absolutely busted. High Priest The'kal now needs to be played in conjunction with healing past turn 5.
It's very niche, though. 90% of the time, this is a vanilla 5 cost, 5/5 that does nothing. It will see play if there is an armor deck in tier 1. Otherwise, it's just another tech card that doesn't make it into the deck.
I trusted all the people say, they won't ever print armor destroy. Now I am sad they were wrong. This doesn't make any sense to game. If Armor is problem, they should have nerf that 5/10 overkill or change how overkill works, don't print this card that demolishes control. The Hearthstone is looking more and more like 5 minute toilet game.. Aggro vs Aggro. Galakrond on 7, gg. Puzzlebox triple pyroblast face.
I think most of the time this function is too niche for this card to see play outside of a tournament setting but its a pretty neat hate card for how low the cost of playing it is. It should probably be like a 5 mana 4/4 or something. That would make more sense.