Dragon's breath and diminishing returns ?Follow

Stuns? No, not as far as I know. Disorienting effects - probably, but there are barely any of those around. I think there's a rogues Blind and a specific hunter shot, but that's it. That said, in a *raid*, in PvE, I don't think diminishing returns apply *at all*. They pretty much do not exist in raids, safe for some specific units (the Val'kyrs on the Lich King for example).