incantation

incantation n.  Any particularly arbitrary or obscure
   command that one must mutter at a system to attain a desired
   result.  Not used of passwords or other explicit security features.
   Especially used of tricks that are so poorly documented that they
   must be learned from a {wizard}.  "This compiler normally
   locates initialized data in the data segment, but if you
   {mutter} the right incantation they will be forced into text
   space."