EEVEE just got GGX Multi-scatter support, courtesy of Clement Foucault, the brain behind the powerful render engine.
Multi-scatter becomes very useful in materials that have high roughness, by better preserving energy over the traditional GGX implementation, which tends to darken around the edges. GGX Multi-scatter usually comes with a noticeable performance hit, but Clement’s implementation attempts to (and succeeds at) make its impact negligible.
GGX Multi-scatter has been implemented in Cycles for a while now, and there are plenty of examples online showcasing the difference and use-cases for this implementation, such as the excellent explanation by Troy_s on Blender stack exchange.