Welp, Keltham's got three healing surges he can use on the day, don't blow through them all at once.
Specifics of required training lean towards 'physically subduing Carissa Sevar after disabling her magic in a surprise attack'. They're not to mention this to Carissa. If anybody's wondering what's up with that or if it's really okay, he's got a letter from Abrogail Thrune about it.