Optics magnifiers? Optics REDUCERS? Ant-magnifier for long range scope to make ultimate rifle setup?

If you can use a lens to magnify an optic, and people in the global war on terror, have use optics to magnify other magnified optics, is it possible to use the opposite of a Magnifier to reduce your scope down to one power so that you can leave your long range scope on a rifle and use it up close? Probably not as efficient as putting a red dot on top or to the side, but still it is an interesting idea.