Ratio of differential count rates from warm-hot phases, relative to the hot ICM. Same as in Fig. 14, but for the most massive clusters at M₂₀₀ > 10^14.75 M_⊙ h⁻¹ from sample M₄ (top panel) to match the mass of the Coma cluster; and for the mass sample M₃ (bottom panel). The data points are the soft excess emission measured by Bonamente et al. (2022) in the 0.2–1.0 keV band, based on the ROSAT analysis of Bonamente et al. (2003).