Attach to an ally and buff them while lobbing Void missiles at foes. Release waves of corruption that entangle foes with tendrils if they get hit by too many. Pretty much the whole kit, just with different thematic.
Was the idea of a Void Symbiote ever considered? Or was the concept always a familiar?
I think they would have gotten a lot of backlash for basically copying Abathur from Heroes of the Storm. He and Yuumi already have very similar kits. If they were to mimic his aesthetic, too, there would be problems. Besides, the Yordle faction has been long overdue a new champion.
This would be a great skin for Yuumi, regardless.
I thought the same thing first, Yuumi has the kit which could have been given to a parasitic voidborn to give us our first true void support.
However, now I have the feeling that she is the reason this isn't going to happen anymore:
Her suit is a symbiotic/parasitic (depends how much this thing is actually taxing Kai'Sa....) voidborn. The thematic niche is kinda already taken here, even if the kit absolutely doesn't represent it properly. It is sad, but it seems they have to come up with another thematic to give us a void support.
Given that Bandle city didn't get a new champion since 
I wouldn't be surprised if Yuumi was designed to be a bandle champion first and everything else came later.
Also I feel like a void parasite is still possible, but since they are parasites and not a symbiote like Kai'sas suit, they should actually invade the enemy and not his ally.
