Its a pretty good encounter power. Probably about right, I'd value the effect at half a W, and the attack part by itself would be a bit weak without that, so it seems like it probably slides in about right. A little situational, but chances are good you'd find a reasonably opportunity to use it in each fight where it would work better than an at-will. Anyway, the daze pretty well makes it better than one anyway.
Brutal Manipulator - You often physically arrange the scenario manhandling enemies into position where they harm each other your martial exploits which induce an adjacent enemy into damaging their ally deal your strength mod damage in addition to any damage they may already deal to the one delivering the friendly fire damage. Additionally If the one attacked is adjacent to you they also take bonus of Strength mod damage.
Insidious Manipulation - your devious manipulations are a surprise to enemies and you can mark an enemy you have manipulated into being harmed by their allies and transfer that mark to any of your allies within range. The enemy manipulated into attacking takes Intelligence Mod damage.
The above turns friendly fire attacks into something akin to the misdirected Mark of the Bard...
As-written I would read it as not being able to target allies at all.
Verbiage:Flavor they get hurt by their own ally but they think its one of your allies fault ... Not entirely certain about rules verbiage.Insidious Manipulation - your devious manipulations are a surprise to enemies and you can mark an enemy you have manipulated into being harmed by their allies and transfer that mark to any of your allies within range. The enemy manipulated into attacking takes Intelligence Mod damage.