Now, you can't use any old soul gem to capture a person's soul. You then can use the soul of the trapped creature to make your boots glow in the dark, or whatever you want to do with them. Soul gems start out empty, and in order to fill them, you have to kill a creature while it has the soul-capturing spell on it.Most of the following spells and effects are taken from the Prima Guide, but the ranges and durations listed in the Guide are not the same as those that appear in the.