Geoff writes...

Why didn't the Magus just throw the Grimorum into the body of water the group was in before entering Avalon or burn it with a torch before entering Avalon, instead of forcing Finella to go into a life of hiding from Constantine and forcing Mary to do the same AND abandoning her son?

And, how could Mary just abandon her son like that? I mean, I've heard of the "Parental Abandonment" trope being used for the sake of good drama (and it did turn out to be good drama in Gargoyles), but I find it a little ridiculous that she believed that leaving her only son at such a young age was the best course of action.

Oh, and here's that trope if you're interested (I <3 TVTropes):
http://tvtropes.org/pmwiki/pmwiki.php/Main/ParentalAbandonment