You should chance the card text. Right now there is a conflict between the image and the notes. According to the image, "Physical damage is reduced by X, where X is the amount of damage you have taken divided by 10" suggests that if a 500hp opoment has taken 490 dmg, he will have a 49 dmg reduction shield while the formula states a ([Max HP] - [Current HP]/[Max HP])*10 dmg reduction, which is 9.