OK. Face-Off closed! Final score:
MIST BALL - 5
LUSTER PURGE - 4
I have to wonder though, what exactly does Luster Purge mean? I know what purge means and I don't think there's such a word as luster (unless it's someone who feels lust..

). Anyway, next face-off is :
SEISMIC TOSS VS.
NIGHT SHADE
Pretty obvious one here, no? They both take off HP equal to the attacker's current level. So, if a Gengar or Machamp at Lv. 100 uses the move, it will take one hundred hit points off the enemy. Fairly simple concept to grasp. My vote is for Night Shade because it seems so scary and mysterious and for a while it was the ONLY ghost type attack which dealt any damage! Thank god for Shadow Ball... Vote away!