So, we're getting upgrades for Cecil, Kain and Rydia in less than two days. Everyone (including myself) is mostly excited for Cecil, and that's easily understandable, but I'm also curious about 5-Star Kain.

Currently, at 4-Stars, he has Jump (x1.8 damage after one turn, basically useless) and High Jump, which doubles Jump's damage (so, to x3.6, acceptable). At 5-Stars, he learns the Dragon Dive skill (x2.1), which, boosted with High Jump, deals a total of x4.2 damage, which is nice, but not good enough to compete with Barrage users. However, he also receives a new passive, Dragoon Spirit, which increases Jump and Dragon Dive damage by 120%.

But how does his Dragoon Spirit stack with High Jump? Is it just an additive 220% total damage increase (x6.72 total damage on Dragon Dive, making it stronger than Barrage) or do they stack multiplicatively, for even higher damage?