I noticed recently that a mod is gaining some notice in the Guild Wars 2 discussion. The mod makes several changes to the way combat and targeting function, with the goal of creating a more fluid, faster paced system. As several have pointed out, Arenanet has strictly prohibited any form of modding to Guild Wars 2, as written in the Terms of Service.
While no one has reported being banned for using this mod yet, the possibility that Arenanet could strike the mod as illegal is still very real. The somewhat vague response from CC Eva in the Guild Wars 2 forums should serve as a warning:
Hi everyone.
As Diva points out, the use of third-party software is not allowed in Guild Wars 2. Thypari, if you feel this is something that would improve the game, then we invite you to post your ideas on the subforum Suggestions, where they will be looked into.
MMO Fallout 