Def piercing ignores a specific amount of a units def. Same with Res. If you have Slash res piercing +10, that means if you attack a unit with Resistance to slash, it’ll ignore 10 of their res number. Doesn’t have to be innate, you can gain it from several VC cards now, even Aigion allows piercing.
I guess square enix decided to let gumi loot the 🔥 out of the players, most of these new VCs are basically 🔥 for whales and an impenetrable barrier for everyone else.
All you have to do is plan ahead and save your viz for months at a time, sinple