A method for arbitrarily controlling the phase progression and power flow of electromagnetic fields within a region of space is introduced. Specifically, we describe how a 2D inhomogeneous, anisotropic medium can be designed that supports desired spatial distributions of the wave vector and Poynting vector direction. Plane-wave relations in anisotropic media are used in conjunction with an impedance matching process to find the required material parameters. The developed formulation allows one to independently tailor the phase and amplitude of a field profile. The work will find application in the design of electromagnetic or optical guiding structures and radiating apertures.