Ok so idea just came to me about how they wanted everyone to see ICC with the buff. To me it helped bad players to much. When ever they release the last Raid and they decide to make another similar buff, why not have it so for every wing you clear you gain the option of a personal 5% that stacks to however many wings they have and you can only gain it with the achieve. Of course I'm using ICC as an example.
Since there are 4 wings in ICC-
First Four=5%
Unholy Wing-10%
Blood-15%
Frost-20%
Lich King-25%
Thoughts on how to improve or if you like the idea?