The equation “\mathrm{DR}_{\text {total }}=1-\prod_i\left(1-\mathrm{DR}_i\right)” can indeed be used to calculate the total damage reduction (DR) when we have multiple sources of DR.
The interpretation of the equation remains largely the same as my previous explanation. The variable “DR” now represents the damage reduction provided by each source or method, and “i” represents the index of each source or method. The product symbol, ∏, indicates that we are multiplying the damage reductions of all sources or methods together.
The term in parentheses, “(1 – DR_i)”, represents the proportion of damage that is not reduced by each source or method. By multiplying all these proportions together, we get the probability that the damage is not reduced by any of the sources or methods.
Subtracting this probability from 1 gives us the total damage reduction, which is the probability that at least one of the sources or methods will reduce the damage. Therefore, the equation is saying that the total damage reduction is equal to 1 (i.e., 100%) minus the probability that none of the sources or methods will reduce the damage.
In summary, the equation can be used to calculate the total damage reduction provided by multiple sources or methods by taking into account the probability that each source or method fails to reduce the damage.