User blog comment:Linathan/Unit Spotlight: Fei and Fang/@comment-74.15.209.213-20150524172100/@comment-26140304-20150524172830

With meta leads that are currently released in the game, like Feeva, Diana, etc., it's relatively easy to get your SBB gauges filled almost every turn. As for enemies that have BB drain, every unit is going to have to run into that problem and you have to adjust your team to cope with such effect.

As for ignore-Def on SBB, it's currently bugged for Fei and Fang. Gumi is looking into fixing that in the future. Even without ignore-Def, there won't be a significant increase in damage as there are units that have low Def stats. Also, I gave Fei and Fang's SBB a 10 due to the fact that it offers a lot of utility. It provides the second highest Spark buff in the game and it increases BB gauges by 9 BC, which is also the second highest in the game. If you compare Fei and Fang to Rosetta in terms of roles as sub units, Fei and Fang outclass Rosetta in terms of damage and utility.