If your Mibyllorr has magical elements, use Warpstone Glow and Moot Green for a classic baleful light. If you'd like to refine this further, I can help with: Creating a full shopping list of paints. Explaining wet blending for her robes. Detailed basing ideas for a Slaves to Darkness army.
Use the same black armor recipe as Mibyllorr to maintain unit cohesion. Citadel.Colour.Masterclass.Mibyllorr.Darkfang.C...
These small models are perfect for practicing specific textures without the pressure of a full unit. If your Mibyllorr has magical elements, use Warpstone