Spike sighed.  "To be truthful, I don't know exactly what sort of ritual he intends to use.  The basic idea is the Law of Contagion.  Two objects, once in contact, continue to interact even after contact.  It's used all the time to direct or anchor spells.  And the Claim is one hell of a point of contact.  But the thing is, most spells aren't in plain English.  And something powerful enough to track him down sure won't be.  Probably won't even be in a *human* language.  I might understand what he's saying, but you won't."