not mentioning fact that there is no system message when this skill does magic critical, i bet that this skills magic critical damage is not counted in overall damage landed on your oponent at olympiad stadium. if im mistaken sorry.
didn't try it personally (do not own an iss dc) but what a friend told me is that the dot cannot crit (obviously), but the first hit (when you land the skill) can crit, thus taking in account your m. crit damage.