Alright. Variance works basically like this:
If you had your TYPE set to a positive number, then it uses a standard number to determine variance. If you, for instance, had a poison type 1 that dealt 50 damage with a 10 variance, then you could take anywhere between 40 and 60 damage (Both of them being 10 away from 50).
If your TYPE was set to a negative number (meaning that everything is in percentages), then a percentage is used to determine variance. If your poison had a type of -1, 50 damage, and 10 variance, then you would take anywhere between 40% - 60% damage (out of your max).
I hope this helps, Susys. I'm glad to hear that you like it.