# Two 25% Damage Reduction sources are worse than one 50% source - DR stacking math punishes fragmentation

All independent Damage Reduction sources combine multiplicatively (1-(1-DR1)*(1-DR2)*...), which means the SAME nominal total DR% delivers less real mitigation when split across more sources than when concentrated in fewer, larger ones.

Diablo IV patch 3.2.1. Category: defensive. Evidence: Confirmed.

## Detail
This is a direct, important consequence of the multiplicative DR-stacking rule that is easy to miss when comparing gear pieces by their printed percentages alone: 25%+25% naive addition suggests 50% total DR, but the true combined value is only 43.75% (1-(0.75*0.75)).

## Why it works
Multiplicative stacking means each additional DR source only reduces the damage that got THROUGH the previous sources, not the original 100% - so splitting a fixed total percentage across more sources always under-delivers relative to one large source of the same nominal sum.

## Numbers
One 50% DR source = 50% total mitigation. Two 25% DR sources = 1-(0.75*0.75) = 43.75% total mitigation - a meaningfully worse outcome for the same nominal '50%.'

## How to use it
When two defensive gear/Paragon choices offer the same total nominal DR% split differently, prefer consolidating into fewer, larger DR sources over spreading the same total across many small conditional ones.