The night is a veil which both protects and harms. The moon can illuminate a beautiful field, or it can hide to aid the approach of an army. Aasimar with strong connections to the Twilight domain understand this balance well, and know that it is their duty to guide the worthy and the faithful through the night unharmed.
Most of the Duskmaster Aasimar find themselves under Nir, God of the Night. However, Elyrr and Aetheria, both of whom have the moons within their domain, have these aasimar under them as well. There are a handful of Eidals that may have a couple of Duskmaster Aasimars as well.