I think Void is a great element in the game, but it's definitely one that causes grief. I'd like to see it adjusted to where it's still good but not OP.
For starters I'd like to see Void Spike 1 and 2 be given a Min_fatigue of 50. There is indeed something slightly exploitative about Void Spike 2's spam-ability at 30. If you catch someone with no mana you can pretty much keep them there if you're a good shot, and that isn't fun.
Also, UV sucks. If you get UV you are sacrificing either Expulse 2 or Armors, so it really needs to be worth it. Since Manaball 2 was lowered to 21, it took UV's niche as "the spell you combo with MS". UV needs to have a new niche, beyond just being another Void spell.
I think the perfect tweak for UV would be to make the splash forgiveness larger and increase the splash radius. Such as, targets within 96 radius of the center receive the full drain, and after that up to 160 receive the current formula for splash. To compensate for this we should lower the damage to something negligible, from 1 - 60 to 1 - 10.
This would repurpose UV from being "just another Void spell", to a very niche, very clutch spell that you break out when you want to void an entire team.