I don't like the Veigar changes on PBE.
I think it's possible for the kit he's got on the PBE to work, but I feel like it will be less satisfying to play. I think we can keep the feel of Veigar's current kit without making it feel so incohesive.
I'm gonna churn out a kit idea here off the top of my head instead of taking apart what's on PBE to avoid becoming a tl;dr mess.
Equilibrium His passive is mostly fine. I think some of his mana costs could use some tweaking, but that's not something I want to get in to the nitty gritty of in this thread.
Baleful Strike Leave it as is. Change the AP on champion kill to 3 on kill and 2 on assist across the board rather than gaining 1/2/3/4/5 only on kill. Now there's less pressure to use his kit less effectively in order to "secure" kills from allies.
Dark Matter Right now it's a delayed meteor strike that synergizes best with snagging them with the stun, otherwise it never hits anything but minions. Keep the delayed meteor as is - but nerf its base damage and ratio by 40% and make it cause a delayed burn and slow in a larger area (~300 range) around the impact site, to make it in to an effective zone control ability and synergize better with Event Horizon.
Event Horizon Here's what I'd change the most.
Instead of a ring shaped stun, change it to an inwardly swirling black hole-looking pattern on the ground of the same size http://www.netanimations.net/moving-animated-swirling-space-black-hole.gif that slows enemy targets (30/35/40/45/50%) that try to walk away from its center (walking around or toward doesn't slow), and speeds up Veigar (10/12.5/15/17.5/20%) when he walks toward the center.
When initially placed, Event Horizon interrupts channeled abilities. If an enemy uses any form of blink, dash or Flash away from the center of the Event Horizon they are briefly stunned. If the mobility move causes them to leave the Event Horizon, they are forcibly repositioned back to the edge of the Event Horizon they left through during the microstun.
Now this is a cage that forces some real decision-making.
Primordial Burst This ability has to be a skillshot. With the added zone control of Event Horizon and Dark Matter I think this gives Veigar a much better chance of hitting this ability though.
Turn this ability in to a projectile that arrives at whatever specific point Veigar designates (1200 range) and lasts for exactly 1.5 seconds (including travel time) before it detonates in a 250 range circle. When it explodes, it takes the AP of all units caught and adds it to its damage, but the damage is evenly split. Only hits champions.
Just spitballing here. I feel like Veigar does need counterplay, but the current kit changes make him more unreliable. The ideas I came up with were with the idea of going with that concept of unreliability and making it in to a zone control kit with a chaos-centric theme. It'll make him a much more interesting team fighter while leaving all but his Q potentially dodgeable.