Originally Posted by
kaiadam
The second biggest difference between 25s & 10s (I might be biased, but I raid heroic modes on both) are spatial mechanics and how they handle them differently. The biggest difference of course is that 10s has significantly more lenient dps checks but that's an argument for another thread. Ball lightning, for example - you simply cannot execute this mechanic in 25m without near-perfect positioning, a gorefiend's grasp, then chain stuns; it's literally impossible. In 10m you can afford to let them jump around a bit, in 25 the (majority) must die before the very first jump or else the raid wipes, and that is the most important change from normal -> heroic for 25m.
Diffuse lightning is another one of those things. We don't have the luxury of overloading it in 25s because the headache of making sure the raid is perfectly spread + the significant amount of aoe that even one diffusion add does is more troublesome than just soaking bouncing bolts.