Relative overdensity probability, P(overdense ∣ M > M_h)/P(overdense), as a function of halo mass threshold, M_h, based on 10,000 mock fields from the simulation. This quantifies the excess probability of an overdensity (at the 3σ level) in a mock field, if it contains a halo more massive than M_h. Curves show the median result from 500 independent realizations, with shaded regions indicating the 68th percentile range. Results are shown for three redshift windows: 7 < z < 8.5 (pink), 8.5 < z < 10 (purple), and 10 < z < 11.5 (blue). We also mark the range of relative overdensity probabilities, conditional on a field containing an M_UV < −20.5 source, observed in BEACON DR2 as the shaded region.