Talk:Thunderbird Sabre Diana/@comment-69.29.129.150-20150425113543/@comment-114.124.34.95-20150425152805

you just have to unlock that unit *7, when his/her UBB unlocked, it would say something like this

"(skill name) has been unlocked"

"(extra skill name) has been unlocked"

something like that...

except for some unit like 6 heroes, they need their respective sphere to unlock their extra skill,.. not just 6 heroes i think, some other unit might need it too,..