HP Challenge - Day 26 Spells

I think today's theme should be what spell would you want to do, not what spell would you want to do without a wand. However I will answer the original question. To be practical if I could only do one spell without my wand I would do Accio, so that I could get my wand. But just for fun I think that I would want to be able to preform Stupefy. There are just some people you don't want to deal with, so getting them out of the way for a bit seems okay.