some changes to maw active?

i just finished a game where enemy team had 2 adc and 2 mages the point is that maw of malmorius passive/active should give you shield when you need it the most and that in this case is against mages not against enemy adc with static shiv/rfg so can you make small change that maw will not get proc when taking dmg from these items? and some masteries maybe too like grasp of undying alone atc