As of Seeds of Destruction (and perhaps earlier) there are now 9 ranks of Radiant Cure. I don't know what they cover or don't. RC2 does not cure Malis (level 75 spell cast on me by Bloodmoon shaman in Loping Plains), but the Malis page suggests that a second cast might have done the job, or a third rank of RC. I'll try both of those ideas next time I have the effect on me, and find out!