More a creative use of mechanics, but it still got nerfed/broken.
During vanilla, a guild having issues with Panther boss in ZG, came up with a unique way of dealing with them. http://www.wowhead.com/item=7375
The original version of that item could effect the panthers that spawn during said fight. Word spread about that strategy and soon after, Blizzard nerfed the item's effectiveness.
I hate it when Blizz does that.