Square Kilometre Array mock Faraday RM observations of Halo3 for three different redshifts. The panels have sidelengths 40 kpc (left) and 2R₂₀₀(z) (middle and right), and a projection depth of 2R₂₀₀. The virial radius R₂₀₀(z) is indicated with the solid circle. The central part of radius 20 kpc, indicative of the BCG, is shown with the dashed circle. Observations of the magnetized (proto-)BCG are possible as early as z = 6.2, where the cluster center shows high RM values, reflecting the interaction between AGN feedback and the magnetized ICM. From z = 4.6 onwards, the entire cluster center and the magnetic field morphology can be studied with a dense enough grid of background and embedded polarized sources. At z ≤ 3.5, the magnetic field can be studied out to larger radii using Faraday rotation.