That we do not yet know. [ Arthur isn't going to correct him. He, too, doesn't do science. ] A group making a mockery of knighthood by calling themselves the Knights of the New World seem to be the culprits, but their identities are unknown. It is something I intend to uncover once we deal with the answer to your second question. To fetch Excalibur, we need to leave Avalon. If we leave Avalon, time is stopped. If time continues, the multiverse will be torn asunder. Merlin has told me that unfreezing time around a singular, moving subject is much more complicated than freezing a large but fixed location.