after spending some time of reseacrhing some of the chinese webs, I finally come to the conclusion about the supercell skill. The skill description in PWI is not wong, but they missed 2 words. It should says 3 thunders: deals an additional base magic attack plus 230% weapon damage plus 4293.2 as PHYSICAL DAMAGE (missing these 2 words). The confusing thing here is that the physical damge is not only just 230% weapon damage and 4293.2 but also included the base magic attack (like archers' metal skills, they include the base physical attack). Basicly, with 3 thunder balls, supercell's damge will be doubled then the total damage will be divided into 2 halves. One half is metal (as the basic effect of the skill), and the other half is physical (as a special effect of 3 thunder balls). I already tested this in AEU on the snake and elk like mobs ( to collect bones for matrix) they both suffer roughly the same amount of damage.