Avoidance Percent (dynamic data)

[ObsidianDragon]

they don't add, because each is a separate check - the total avoidance is the chance that one of your avoidance methods will kick in on any given attack. the way to find it is to calculate the inverse, that is, the chance that all avoidance chances fail, then subtract it from 100%

total avoidance = 1 - ( (1 - base) * (1 - block) * (1 - parry) * (1 - deflection) )

in your example:
total avoidance = 1 - ( (1 - 0.238) * (1 - 0.174) * (1 - 0.080) * (1 - 0) ) = 0.42094096 rounds to 0.421