Kill other fae for the bragging rights: sounds pretty fae to Lambert. Well, he doesn't have any particular desire to get involved in this, but there's only one specific reason he really has any investment in asking this question:

"And what's going to happen to the rest of her court? The changelings, everyone in her service? Are you going to kill them too?" He's pretty sure the answer is 'no' but he'd like to hear it from the beast's own mouth, so to speak.