I've been racking my brain about this and searching forums for who knows how long, reading through tons of codes, api scripts, mods. I've never been able to find a way to do this with 3D dice working. Honestly rolling an attack with 4d6 on it and 8d6 rolling made me want to explode. Then I did a custom game that critical worked different it was even more annoying having so many dice. I didn't want to write macros or make other complicated scripts, it honesty seemed like it should be really simple thing to accomplish. Then it occurred to me while learning about the rolling scripts that I could just trick it into believing I can't even roll critical... All I had to do was change the CRIT field to a "0d0" on the attack button (for whatever it was weapon or not) the extra dice disappeared... I've seen this question asked so many times and never a simple answer formed or even an answer given to the problem. So this is basically just a helpful tip, for anyone still wondering.