I was wondering how casting weapons are triggered to cast in combat? Do you get a "natural 20" roll on the mud, if so do some weapons have a larger % chance to cast? Also does the weapon cast on the same critical hit as a ranger's double damage critical or different?

I think it's an intelligence check to cast. I don't know how it's determined in numbers. And I believe it's a wisdom check to see if you are zapped by the weapon when it does make a casting attempt. Borgs automatically fail. I have not noticed critical hits having any correlation to weapons casting so I don't think they both are a function of roll to hit.

Borgs do not automatically fail. If it is a casting weapon that casts an electric spell, they automatically fail. Heartsbane got all the way to gen 10 using a casting Acidic blade. They still have a higher probability of shocking borgs, but borgs definitely do not automatically fail.

Well that's good to know. I don't know if that's a bug or a planned difference because the acidic doesn't cast magic, it alter's a phys spell. I have never seen or heard of a borg not being zapped by a weapon that actually casts a real spell, but I never tried one that did alterations or triggers.

I can confirm that a cyborg does not get zapped by alterations or triggers. It makes sense when you think about it. A cyborg by it's very nature is a creature of science.

I'm fairly confident that a secondary cyborg doesn't get zapped by magic weapons either.