Quote Originally Posted by sanahtlig View Post
As I understand, the Burst modifier cap is +300%, which is expanded to +500% only when Shingen's HP weapon is equipped. 3 SLVL20 or 2 SLVL30 Union weapons with Exceed skill will get you +90, and 3 stacks of Asherah buff will get you another +90. That limits the benefit of Provisional Forest to +120 or +320 (don't forget to factor in the -10 to -15% damage from running HP instead of elem ATK skill).
According to the wiki the burst modifier (soft?) cap is a solid 500%. Shingen's HP weapon increases the amount of burst damage boost, the cap stays exactly the same.