A realization I just came to in the Simple Question thread on 339....
A deployed (psychoactive) skin completely covers the wearer and all his equipment, but allows him to see, hear, and breathe normally
MDJ is a burst. Bursts require
Line of Effect to affect something. Anything that blocks LoE blocks the spell from affecting things behind it. Something covering your entire body would block LoE to everything on your body.
Similiarly, AMF is an emanation. Emanations also require LoE in general. So anything that blocks LoE can block an AMF, and prevent it from affecting things behind it. Enjoy!
The discussion was about protecting your gear from fire/lava, and someone suggested wearing one of these over it because they cover your whole body. If it works for that, it will also block AMF/MDJ, and just about everything else...