Refinements:

Every 4s a character is on the field, they will deal 6%/7%/8%/9%/10% more DMG and take 3%/2.7%/2.4%/2.2%/2% more DMG. This effect has a maximum of 5 stacks and will not be reset if the character leaves the field, but will be reduced by 1 stack when the character takes DMG.