My power would be the a variant of the "Scanners" power.
I would never want to actually kill anyone, but knocking them out for 10 minutes would be great.
1. Driving and seeing A-hole who is tailgaiting me in an attempt to morph through my car....... ZAP, time for a ten minute nap by the side of the road.
2. Yeah, I know you are in a grocery store trying to pick out the right canned pudding for your fat kids, but get your cart out of the MIDDLE of the isle so I can get around. ....... ZAP.
3. Hey moron, I know you are enjoying the sporting event, but stop screaming curse words all night as there ARE kids present...... ZAP.