mesmer's elite skill: Panic

http://wiki.guildwars.com/wiki/Panic

Is the target foe also interrupted when successfully activating a skill? or only nearby foes? Thanks.

No. Target foe will interrupt all foes in the area when it attacks, but the hex hits everyone in a large AoE. You get a chain effect where the larger the mob, the longer none of them will be able to cast and get interrupted. THe fact that it gets better with size of mob means it's irrelevant in 80% of the game, give or take.