Ghosterling... you're pretty hard to hit when you're ghost element sweatdrop although the doppleganger card also sounded pretty cool... always fast attack.
I have personally used a dopple card on my Natural Crit Sin on Loki (I found the card from dopple on my second time killing him whee ) and trust me when I say that your attack speed goes through the roof. My account was deleted awhile after because a guild member reported everyone in my guild for suposedly botting when he got kicked out of the guild..... many many pissed off people