There's a trick that allows you to toggle the turning on and off of the magnification of the Dock in real time. Just hold down the Shift and Control keys at the time you are over the Dock.

If you have magnification on, this will turn it off. This can be handy when you are trying to grab something on your desktop and the magnification keeps moving the dock into the way so that you can't grab what you want. This instant-off of the dock magnification fixes the problem.

If you have your dock magnification off, holding Shift and Control when over the Dock will cause the magnification to turn on. This can be useful if you don't normally like the magnification but you want to turn it on for just a quick minute to resolve something that you can't quite see.