On Store, does Mastery Upgrades increase “xp gain bonus” or “mastery xp gain”?
Also, what is the difference between both?
It affects mastery xp gain, that's how much mastery xp are you going to get after you die. The formula for it is skill_lvl * multipliers.
Xp gain bonus is the effect of mastery, multiplier to normal xp gain (1.2^mastery).
