Help with giving entities potions

Hi there! im having some troubles and am looking for some advice. First off should mention im doing this on 1.12 with Mcreator version 2020.2

So, my intention is to have a item that has two functions. Give the player a potion effect, or give a mob the same effect. ive tried a number of things, from having the left click be what gives the effect. that diddnt work as it would no longer consume the item. and ive tried having both functions to the right click, but it would always give the effect to both myself and the mob rather then just one.

So, how can this be done?