User blog comment:Iceburger/Smarter, Faster, Stronger, Superior in Every Way - 7* Grandt Edition/@comment-26944381-20160318031839/@comment-27842868-20160318222026

The way the UBB buff works it that for every critical hit a unit inflicts, that unit gets a 20% boost to ATK and BB damage. With him in your squad, you would focus more on criticals.