With the adjustments to buffing/debuffing, allowing a target to permanently reduce the target's attack and defense both are an attractive possibility. While games can be over instantly, at the same time battles can drag out sometimes quite a long time. Attaching this sub gives you a shot at weakening your enemy- possibly multiple times if it's on a card you'll want to play at every opportunity like Penguin. She takes the place of a pure skill boost/power up card, but conversely she's an icon-matching SS- she might just give enough in pure numbers to make up over a bad S-rank booster. Consider it based on her chance of success and whether you like those odds, though.