Mercedes Balance Analysis

???

If you even bothered to run the skill data through Google Translate, you'd realise that the defense negation is a debuff to the target and not a true "party buff". Joe refers to it as a "bonus...for the entire party" because it is indeed that; it boosts the damage of the entire party, except not because it gives everybody a 100% chance to ignore defense by 20% for 15 seconds, but because the victim has its defense reduced by 20% for 15 seconds.