I apologize for the misinformation. My words regarding the percentage decrease are incorrect, as I performed the calculations using 2% instead of 2.5%. Indeed, when attack is lower than defense, the calculation formula is exactly as AmberSoler stated. That is, the base damage is multiplied by 1.3, and then by the coefficient derived from the difference between attack and defense. However, here is what I want to clarify: if attack is higher than defense, there is no multiplication by 1.3; instead, 30% of the base damage is added to the calculated result. This can be seen in the attached file. The hero has expert Offense. The base minimum damage of vampires against butterflies is 48*5=240. If we apply all modifiers, we get 240*1.3*(1+18*0.05)=592.8=592. We can see that this is not the case. The correct formula is 240*(1+18*0.05)+240*0.3=528. Or 240*(0.3+1+18*0.05)=528 (which is the same thing). Thus, the damage calculation formula with Offense is DIFFERENT depending on whether the attack-defense difference is positive or negative.