[Gameplay] Devourer Ekko

when i build devourer on ekko and use E and attack something it deals damage to me. from time to time when i E on a monster i notice a bit of damage taken before the monsters attack ,once i even checked my death recap and I had an assist on my own death it said that i dealt 63 damage with devourer and the other thing i can't remember maybe it was the W passive or E