MSpectralDynamics can do many things, but mostly it serves as a modern hi-tech replacement for multiband compressors and loudness maximizers. However with features such as custom processing shape it can provide a wide range of effects. Additionally it provides a free-form linear phase equalizer with range from -80dB to 0dB, which you can use to fix issues with your recording.
Unlike Multiband compressors, MSpectralDynamics does not have any bands but works with the entire spectrum instead. It approximates energy located in each frequency and applies the dynamics to it separately. You can perform spectral compression to balance the spectral energy and increase loudness with minimal amount of artifacts. You can apply spectral expansion to excite frequencies and increase sound clarity.