Brave Barrage

Extra Skill

ES

Brave Barrage

Boosts Atk relative to how high remaining HP is & boosts Def relative to how low remaining HP is

Buff Values

HP Scaled Boost

ATK buff0-150%
Scales withHP remaining
TargetSelf

HP Scaled Boost

DEF buff0-50%
Scales withHP lost
TargetSelf

How to obtain

Rare Summon Promotions

1 Global Exclusive Elgif every 10 summons

Prosperity Bundles

Prosperity Bundle 3 ($34.99 USD)

Obtain from Frontier Hunter with HR 124

Source: Brave Frontier Wiki