The boggart is a ghost-like creature that usually resides in dark,
closed spaces such as a wardrobe or a drawer. No one knows what a
boggart's true form is because every time a person tries to look, the
boggart shape-shifts into the thing that the person's worst fear is. Its
lifespan is indefinite. However, if a boggart turns into a magical
creature such as a dementor, its magic will be weakened. So if the
boggart/dementor approaches you and gives you the Kiss, it probably will
not have the full effect has a real Kiss would. When facing a boggart,
it would be better to have someone accompany you in order to confuse it
and give you more time to kill it.           There is only one
way to completely finish off a boggart, and that is laughter. However,
in order to disable it so you are not so scared out of your wits that
you are unable to laugh, there is a spell. If you visualize something
funny, point your wand directly at the boggart and shout, Riddikulus!, that
thing that you just thought of will appear on the boggart, which will
confuse it. It will also give you more motivation to laugh!