straight from DialogueActions update log.txt
da.random {read only} - returns a random value between 0 and 1. Example usage to make it 1-10: (you'll have to define x as "*" in initial_settings to get access to multiplication operator) [VA_SET_VARIABLE_var1_*da.random x 9 + 1 \ 1*] - formula is ( random * ( max - min ) ) + min \ 1
PS: I never used that feature, I hope this helps.