My next step is to paint a monochromatic underpainting to work out the values and lighting for this painting. This is not a step I normally bother with in my smaller work, but, this large, complex composition is purely fictitious with no reference outside of my imagination to rely on, so, I need the value study to help me work out these details.
This is painted in using just white and burnt sienna.
I added a little ultramarine blue and burnt umber to create some deeper dark values here for the back room and for detailing on the centaurs.
I am not finished with the value painting, yet...just had to quit for the day. I am not so much interested in creating every little detail in the monochromatic study, but, I do want to fully establish the lighting/shadows at this point and make sure it works well in the composition before I start adding color.