"Buddha wird erscheinen, wo er gebraucht wird."

Translation: Buddha will appear, where he is needed.

[rkaup]

Can someone explain to me the role of the second "wird"?

[kyky]

It is needed for the passive mood.

[Germandy]

As kyky said, it is needed for the passive voice and it comes from the verb "werden" (to become). Found this website that I think will help: http://german.about.com/library/weekly/aa012901a.htm