Synthetic spectra generated using the Monte Carlo scattering code, where three of the four parameters were held fixed while the fourth was varied: optical depth τ in panel (a), maximum velocity v_max in panel (b), shell width Δr in panel (c), and inner radius R_in in panel (d). The colorbar indicates the value of the parameter being varied in each case, while the values of the fixed parameters are noted in the title of each panel. The Δr and R_in are in units of photospheric radius R_ph and the colorbars are in logarithmic scale for better visualization. For clarity, the host galaxy Mg II lines (black dashed lines) have been excluded from the model spectra. The gray curve shows the observed spectrum of SN 2020rmv, with the light blue shaded region indicating the 1σ uncertainty.