To clarify from previous posts:
Last night we hotfixed part of the Nefarian encounter. Specifically, you should no longer be able to stand on various parts of the geometry and cause the Drakonids, Nefarian or the skeletons to go into evade mode.
Forcibly trying to put creatures into evade mode is considered an exploit, on any encounter.
As for crediting serverwide first kills as legitimate or not, that's not something that we've ever done. If we felt a specific guild was exploiting an encounter or had exploited an encounter to defeat it, our GM staff would contact them and take appropriate measures.