http://yugioh.wikia.com/wiki/Mirror_Force

I've got no clue if this one has been put into YGOPro or DevPro yet but it would be nice to see it.  Yes it's a bit broken under some conditions but not nearly as bad as I thought it was going to be.

Anime Mirror Force's Effect:
When an opponent's monster attacks, negate the attack. Then, destroy the attacking monster and all Attack Position monsters your opponent controls. Any difference in ATK between the destroyed monsters and the attack target monster is inflicted to your opponent as Battle Damage.


Figured it would be interesting to see. :p