Maglubiyet's stated NWN domains are Death, Trickery, and Destruction. Either Death or Trickery is not an appropriate domain, so spells cannot be cast due to an error in domain choice.

I have two thoughts as to why this may be:

1) Death is not supposed to be an appropriate domain, as considered from some previous research of mine.

2) The server's information, i.e. the system/coding that determines if domains/deities are matching has the wrong information.

Any news about this?

And sorry about that TheBeggar, it was somewhat of an emergency when I had to jet!

That information was incorrect. In our deity system, he has the domains Chaos, Destruction, Evil, and Trickery. I've updated his deity profile in the Faiths of Faerun section to reflect that.