Composite spectral analysis of J1538+0842. The LAMOST spectrum (black) is compared with an MWD template with a surface field of B ≈ 12 MG (dotted red line) and an M0 star template (dashed red line). While the MWD template fits the Zeeman-split Balmer lines in the blue channel (λ < 6500 Å), the M0 template is required to reproduce the molecular bands in the red channel (λ > 5500 Å). In contrast, the SDSS spectrum of the same target (blue), scaled for comparison, shows no significant M star features in the red channel.