Mass weighted histograms in the magnetic field versus gas density plane (upper two rows) in the ICM. Adiabatic compression of a flux-frozen magnetic field implies B ∝ ρ^2/3, and a self-gravitating system with a saturated dynamo scales as B ∝ ρ^1/2 (see black dashed lines). The radiative simulation starts to deviate early and first at high densities (corresponding to small scales) from the adiabatic relation, hinting toward dynamo activity at high redshifts. A rapid growth and early saturation is visible. By contrast, in the non-radiative simulation, magnetic amplification is significantly delayed and saturation is only reached at z = 0. The lower row shows the magnetic field vs. metallicity histogram in the ICM. The contours of constant density are indicated by brown-orange lines. These panels illustrate how the magnetic field is first amplified in high metallicity gas (in the center) and then, subsequently, in lower metallicity gas. The correlation between both quantities highlights the contributions of pre-enriched gas (in magnetic fields and metals) from merging galaxies in enriching the outskirts with both magnetic fields and metals.