In other words, a second book in a series. Some new characters, but mostly old characters getting some more backstory and shading to their personality. A bit more about the characters-that-are-the-races: the elves are there to hold back some seriously scary bad, and have sacrificed the majority of their immortal members to the cause (which is fairly disturbing, actually, but it's Luna, so no surprise there). The one thing that keeps Kaylin from being a complete Mary Sue (utterly lame fantasy wish-fulfillment character who solves every problem but is otherwise completely uninteresting) is the scale of the problems she is involved with -- well, that and the fact that she's got lots of powerful allies who she needs to get anything done at all.
I'm starting to think of the Mark from Nightshade (remember the spidery blue flower on her cheek? No, the cheek you _see_) as her Star Trek communicator. Or maybe one of the people she gets to call to ask for help on Who Wants to Be a Millionaire? Whenever she's somewhere totally inaccessible and stuck, she can always request assistance from Nightshade, or, now, the Lord of the West March. Will Severn be calling her in future books? Will she be "seeing" through Severn's eyes and "listening" through his ears? Oh, I'm sure we'll be finding out soon; after all, there are three books in this bundle.