Time Flume

I would choose to be able to cast the spell to freeze and un-freee time. I would just say the spell and then list the amount of time that I needed it to be frozen for. I wouldn't want to go back in time or in the future because then I could potentially mess everything up and cause a black hole or something like that. Plus I could do a lot with that spell freeze every thing and then sneak on to a plane to Maui  and  be back in 16 hours. (I have to be gone for the exact amount it would take to fly back) I could stop crimes and it would just be a general good thing. Unless I aged the amount of time I froze time. Then I would be really old and everyone would say jeez you look like your a million years  old and your only fifteen. I would have to use my time wisely.