Maw of malmortius procing without taking magic dmg

hey first time reporting a but so forgive me if it is writin poorly

i notice a few games ago that maw seemed to be procing from olaf witch should be impossible he has no magic dmg also i would like to note that he didnt have red buff cuz that would proc it also i saw it proc from a turret shot witch also shouldnt happen so just putting it out there