To me multiple (light) exposures or shutter speed tricks don't really meet the point of this challenge. It's an interesting picture, but at the same time vaguely unsettling. Interesting, but also, the proportions seem off. (The real head is much smaller than the mask.)
thats just creepy.. lol .. the person behind the mask coming through.. plays with my mind and my eyes... its subtle.. would have liked to see the person behind the mask more..but thats just me.. :) fun picture.