Teras Kasi Archive

When I would get a new skill for Teras Kasi like, for example, Intermediate Power Techniques, it says +15 to damage and speed. The +15 for speed...what does that actually mean? I know there is some sort of formula and somebody figured it out, but I can't find the post anymore. And the +15 to damage, that means my damage goes up by 15 points? I am not sure, but someone clarify this for me please