Buff-stacking model
Bonuses of the same type add together, then multiply across categories. Skill damage is its own lane; enemy-defence debuffs multiply the whole stack.
Total attack bonus
+146%
sum of all sources (additive within category)
Relative damage index
1.23×
effective attack ÷ effective enemy defense (after debuff)
Skill-hit multiplier
1.53×
skill damage is a separate multiplier lane
Value of the next +10% attack
+4.1% real damage
Diminishing returns — fill an empty category (skill dmg or enemy-defense debuff) instead.