Veigar changes, and how they will affect his gameplay, with math
There is a link to the changes as we know them posted at the bottom. I would welcome the input of any members of the balance team working on Veigar, or of any other forum posters.
There are a couple aspects of the Veigar changes I would like to discuss. First of all, Rioter Smashgizmo has stated that the q changes allow Veigar to farm his q more over the course of the game because of the reduced initial cooldown and the fact that it now double hits. This seems to operate on one or two assumptions; first, that Veigar will be able to get more last hits because of the double hit nature of the ability, and that Veigar will get more last hits because of the lower early cooldown. I would call these two assumptions into question.
First, there is no guarantee that two minions will be both at low health and positioned in such a way that Veigar can last hit them. last hitting two minions requires that in the straight line between them, there are no other minions also requires Draven like predictability in positioning since every point Veigar can move to to hit both minions requires him to be on the same line they share. This positioning will also periodically require some very dangerous choices from veigar such as standing much closer to the minion line to get the q double hit if he has to fire it from the side.
The assumption of reduced early cooldown allowing more last hits with q is almost laughable if you think about it. Veigar is constrained by the cooldown at early level, its true, but he also suffers a significant mana constraint despite his passive. Veigar can only cast his q so many times before his first back unless he wants to sit there recharging just enough mana for one q per wave (some starting items or rune pages may allow more) This means that the reduced cooldown actually has little if any effect because veigar will almost always have hit level 5 before first back, and since veigar maxes q first, he will have 3 ranks at that point, which means he is from that point on experiencing an equal or longer cooldown than he used to have.
This also assumes of course that you land every skill shot perfectly, since it used to be a point and click, even pros will have a lower success rate if they aren't landing the double last hits.
The next aspect of the changes I would like to discuss is safety. After these changes, Veigar will need to be practicing potentially unsafe behavior in order to use his q effectively (the positioning issue I talked about before) But he also is being less safe because this new q will result in a more pushed lane.
Since last hitting with q seems to be veigar's only purpose in lane now, he needs to get all of the last hits he can, this means that some last hits are likely to hit a minion that wont die from the hit so he can kill another minion either in front of or behind it. This means that sometimes, a minion will be taking damage that kills it faster, meaning the lane will be more pushed. Most Veigars I have seen prefer to stay almost on top of their turrets, and this change will make it harder.
The changes to Veigar's e also significantly reduces safety. With a delay added before it goes off, there is an entire class of champions that Veigar now loses all opportunities to hurt. Any champion with an untargeted dash can pop out of the circle instantly if they have it off of cooldown. Also, attempts to counter targeted dashes will also be prone to failure due to the narrow hit ring the stun has. Imagine a ulting zed, veigar reacts as fast as humanly possible, and places the stun ring so it passes through his own back, but with the delay, + reaction time, zed gets an almost guarantied get out of stun free card by walking one step before hitting all his damage abilities. The same applies for champions like Katarina, jax, and several others. It also means that if veigar is getting ganked, and tries to put the stun ring between him and either of his opponents, the mobility of the jungler will often allow them to get through the circle and to Veigar, since almost all Junglers these days have a dash, either targeted or not.
Combined with the fact that veigar has to be less safe to q farm, and it makes his weak early game even weaker.
The last area I would like to discuss is damage. In this case, Veigar has taken two hits for one supposed gain.
First, Smashgizmo stated that Veigar gets considerably more q farm and this means his ult needed a lower ratio. Ok, so his ult lost .2 off its ratio, how much more ability power does he need to pick up to compensate for that loss? well, his total ratios went from 2.8 to 2.6 and his only almost spamable spell had its cooldown increased so lets assume a single combo. For ease of use, I will work with 100 ap, 2.8 * 100 = 280, this is the damage he would get from his ap ratios with 100 ap, to get the same damage with only a2.6 ratio, 280/2.6 comes to 107.69. this means that for Veigar to get the same damage from his combo, he would need more than 7% more total ap, just from q farming. To put that in perspective, lets compare at a couple of total ap levels, 100 we have already done, so lets try, 200, 400, 500, 700, and 1000. these numbers will be rounded up to the nearest point of ap
Total AP | Addtional q farm required
200 | 15 additional q farm required
400 | 31 additional q farm required
500 | 39 additional q farm required
700 | 54 extra q farm required
1000 | 77 extra q farm required
This shows that while possible, the extra ap from q farm would be challenging for any number after the first couple. I don't know about other Veigars, but most of my q farm ends up coming from champion kills and I don't see that number going up at all from these changes, (I predict a harsh downward spike instead) and would in turn require even larger amounts of q farm.
It is also worth mentioning that this may significantly underestimate how much additional q farm is required to break even, since it assumes that Veigar's full combo can still be unloaded. Smashgizmo said that Riot wants Veigar to trap people inside his stun circle rather than actually stun them, this means they expect him to be able to land a skill shot with a 1.2 second delay as well as his now skill shot q while the target has nothing to do other than try to dodge. I would say that against most opponents, this is just an exciting way to waste a couple hundred mana, as the dark matter is pitifully easy to dodge if not cc'd.
So in order to do the same damage, Veigar has to farm better than he currently does, and land a combo that is at best, devilishly difficult and at worst impossible (looking at you Zed, Lee, Kassadin, Ahri, Ezreal, Lucian, Shaco, etc...).
So in summery, Veigar's laning phase just got much more dangerous and less reliable, his damage got considerably less reliable (and possibly lower), to the point that in a 1v1, one of his spells might as well not even exist, and his single target spam spell now can hit two targets but has a longer cooldown. The only thing he has gained that I consider an improvement, is the reduced cooldown on dark matter, which might allow him to use it twice in a long fight. if he lived that long. He has lost his ability to 1v1 any champion that doesn't make a mistake.
Veigar was always a champion that punished mistakes, both his own, and his opponent's. If he screwed up and missed his stun gate, then there was a very good chance he would die, and if his opponent made a mid or late game mistake, Veigar could either hurt or kill them. now though, with these changes, it seems like Veigar will be forced to rely on his enemies mistakes entirely, because there is no way a player will get hit by a telegraphed skill with a 1.2 second delay unless they make a mistake, which means Veigar loses around 40% of his damage if he is fighting 1v1.
The change to his stun also means Veigar will lose his niche in the league of mobility, as he will no longer be able to get away or survive being attacked by assassins, and he will no longer be able to catch fleeing mobile champs like lee sin or Nidalee.
IF you insist that this change is good for him, I would strongly suggest that you make his e stun people who use blinks to escape it like it does with dashes, because if not, it will never stun any champion that uses blinks, ever.
Currently, the only place I know of to see the changes is here http://boards.pbe.leagueoflegends.com/en/c/champions-gameplay-feedback/LKAEsmPM-veigar-changes-hitting-the-pbe-soon