Multiple metrics for WD 2138–332 as a function of its rotation phase: the mean longitudinal field, ⟨B_z⟩; combined equivalent widths, W_λ, for the non-saturated metal lines in the ranges 4207 − 4244, 4296 − 4332, and 4369 − 4418; abundance measurements for Mg, Ca, and Fe; and observed and synthetic TESS fluxes (normalised such that their mean values are equal to 100). In each panel, the best sinusoidal fit is also overplotted.