Until watching KOO vs FNC today, I couldn't really think of any "safe" way to reduce his power and just expected Riot to flat out nerf base dmg stats (which will put him in the Azir league of "sucks in solo queue, still broken in pro play").
There was a teamfight mid lane where Veigar cast Event Horizon a total of 3 times before it was over. Spaced around 7 seconds apart each. An AOE hard CC/deterent of that power level shouldn't be anywhere near that short of a cooldwon surely? Considering the power of being able to flat out delete a squishy (which I'm happy for him to do), it seems a bit spam-able.
I've seen some numbers stuff on PBE, but that just looks like the same old "nerf damage>send to bin" balance philosophy we've had with the same hamfisted glory this entire season has faced. Any other ideas on how Riot might actually balance him without rendering him useless again?