OK, time is a form of speed that makes things change their place, form, stage and speed (technicli time as a form of speed changes itself), those four things we like to call dimensions. Dimensions are therefor fused forms that can exist next to another, thru another, or destroy another. People, especialy sf like ninjas full of moveable chakra, can influence, change or even control elements. If someone influences time, he can change the whole dimension (place, form, stage and speed), and the worst posible to change is the place cause if u put dimensions in fixed "holdpoints" of an another dimension the they do 2 things: mix (means that things can jump thru a "door" that we call a black hole, for instance in space), and the second, and more posible destroy eachother. Now, the black holes are proven as "doors" proving the first dimension PLACE, now lets prove speed; when astronauts move with the speed of sound thru space, they age slower, some 30 y/o astronauts allready have grandchildren, so if something would move with the double speed of light, then the time for this would stop, and if u double that speed again then time would start to go backwards.
Therefore, time is the most powerfull element, and therefore uncontroleable...but it is an element!