  We consider, as a simple model problem, the application of Virtual Element
Methods (VEM) to the linear Magnetostatic three-dimensional problem in the
formulation of F. Kikuchi. In doing so, we also introduce new serendipity VEM
spaces, where the serendipity reduction is made only on the faces of a general
polyhedral decomposition (assuming that internal degrees of freedom could be
more easily eliminated by static condensation). These new spaces are meant,
more generally, for the combined approximation of $H^1$-conforming ($0$-forms),
$H({\rm {\bf curl}})$-conforming ($1$-forms), and $H({\rm div})$-conforming
($2$-forms) functional spaces in three dimensions, and they would surely be
useful for other problems and in more general contexts.
