The total damage would still be 3. The base damage for the first RAD would be 2, but then each additional RAD would just add 1 damage (not the base weapon damage again). This would make it work like other all the other weapons. So if Naphta rolled 4 RAD, it would be 5 damage (2+1+1+1) not 8 (2+2+2+2).Example on same page:
Naphta rolls two [successes],
which together with the weapon damage inflicts
three four points of damage on the Zone-Ghoul.
Max four: You can never have more than four mutations. When you draw your fifth card, you have to discard one of the four old cards you have. You chose which one. This means that one of your character's mutations regresses in favour of the new one.
New Mutations: When you manifest a new mutation, just draw one new Mutation Card or roll once on the mutations table in this chapter. You can never have more than four mutations. Read more on page 25.
Not the same. That paragraph that you refer to exists in the Swedish rulebook as well. The missing paragraph that I refer to does not. The missing paragraph that I refer to (that doesn't exists in the English book) explains with more detail what to do if you have four mutations (read the paragraph above).It's in the 3rd printing at least (I didn't go back to check the first two). Page 70, paragraph 2.
New Mutations: When you manifest a new mutation, just draw one new Mutation Card or roll once on the mutations table in this chapter. You can never have more than four mutations. Read more on page 25.