User blog comment:Emptylord/Blogs/Time-themed abilities/@comment-24315274-20131220074936/@comment-8100976-20131220145048

I think the simply suggestion to that Empty would be that the trail left behind corresponds with the effect.

Cast Time Warp on Enemy: Enemy leaves a slow field. (This obviously only affects foes.)

Cast Time Warp on Ally: Ally leaves a haste field. (This obviously only affects allies.)

This makes positioning ever more important; which seems to be in Riot's prefered method balance these days.