Is the back mod working? I ran a few tests and didn't see a difference in damage output. It ticks the same regardless of health level.
I always thought his was tied to a league hall buff. I could be wrong, happens often. I've never tested it but that's what a league mate told me awhile ago.
Yes you are right! The game has two berserker buffs. The first is the back mod, which gives + 10% damage output. The second is the league buff, which gives + 3% damage output. (As I remember)