How much Knowledge (religion) does it take to know that Liches return from destruction... furthermore, whats the DC to even know what a Lich is... or that Xykon is one?
Edit: also, Paladins have some nasty MAD... I'm guessing Miko has Int as a dump-stat.
Actually if Miko does fall I'm betting Belkar will be less satisfied with killing her- plus, she won't be able to call "Miko's stupid horse" anymore, though she'll be able to call an infernal steed in its place. But anyway it'll render that part of the Oracular answer moot.
And actually, if the lawyers show up, I'd be genuinely surprised if Xykon doesn't off them immediately and make them a "job offer they can't refuse," as it were. He may not be Chaotic like Belkar, but he certainly doesn't seem to be Lawful either. And silly mortal lawyers won't be anything he'll allow to stand in his way.
EDIT: Oh, and I agree with Drowbane. INT as a dump-stat FTW.