as of the last time i checked the void gate is like a ward in terms of targeting and damage taken, that is can only be hit by basic attacks. while i understand that it is a way to safe guard the portal if you are being sieged by it there is no way to destroy the thing without either engaging, which risks losing the tower to it, or having a really long range adc be in a vulnerable position.
while you can destroy the voidlings with some poke it can be hard to do so. so i propose a three changes:
1. change the portal to be able to be hit by skill shots, but not be targetable to targeted abilities
2. make it so that it take reduced damage from skillshots
3. make it have a tad more tankyness so that it can hold under a barrage of skillshots for some time