Once scheduled server maintenance is completed during the week of July 17, the "Power of the Aspects" spell will grow more powerful, reducing the health and damage dealt of all enemies in the Dragon Soul raid by 30%. This spell has grown progressively stronger over time to reduce difficulty and make the encounters more accessible. The spell will affect both normal and Heroic difficulties. It will not affect the Raid Finder difficulty.
If you don’t need the help of the Dragon Aspects, the spell can be disabled by talking to Lord Afrasastrasz at the beginning of Dragon Soul.
We hope you continue to enjoy Dragon Soul, and that these changes encourage you to attempt a higher difficulty, or just keep pushing to take down that next boss.
Fuente: http://eu.battle.net/wow/en/blog/5436093
RPV: El próximo reset de save entrará en vigor el nerf de 30% en Dragon Soul.