I'm keeping this separate from the other thread to get focused discussion. If you're lazy scroll down to the TL;DR.
Here's my opinion. For Baleful Strike to be effective, you have to last hit creeps with it all the time, and use it as your primary nuke against heroes. There's two problems with this.
First, in early game, you can't spam it that often, because the mana you're using toward last hitting creeps is better spent using Dark Matter to farm, or Event Horizon to run/chase. If you keep using it early game then you have less flexibility with other spells. Because Dark Matter is key to farming mid game, and a stun should never be passed up, I only get one rank of Baleful Strike. I might as well be spitting on creeps, half the time i manage to score a hit, the other half the creep dies while the projectile is in transit.
Second, in mid game to late game, your primary nuke will be Dark Matter, for farming and for harassing. It simply hits harder than Baleful Strike (because, as mentioned before, it's wiser to levle up Dark Matter early) and you can combo it with Event Horizon for heavy damage in team fights. More importantly, because it hits so hard, creeps will be dying in waves so there's little chance to spam Baleful Strike in order to take advantage of the AP bonus.
Proposal: Honestly, I don't like Baleful Strike at all. I'd like to see the AP gain rolled into Dark Matter, while decreasing the gain to something like 0.1-0.4. Or make it a passive. Vivi's current passive is ****, how often do you hit people with your wand? And how many of them even have AP to steal? Vivi doesn't have a giant casting range, especially since you need to be in position to use Event Horizon. The champions that are the closest targets tend to be tanks, who rarely stack AP. And even then you want to move in and out of range as cooldowns demand instead of staying still and attacking.
A very strong delayed nuke that reminds me of Pugna's Netherblast. It doesn't hit very hard early game but it can be devastating once AP is stacked. I like it as is, but would like to make the location less obvious. The only way for someone to miss it is if they're looking somewhere else or it's cast in a crowd of characters. Otherwise you he to rely a lot on luck to make it hit. It's better than Baleful Strike in so many ways that it is my primary nuke whenever I play Veigar.
Awesome stun with a twist. Which seems to be a theme among all of Veigar's moves. it also needs a lot of planning. Especially if you want to ensure the stun. You can cast it so that the edge touches them and chain it into a Dark Matter. I don't think it would hurt to up the range a little bit. I'd like to be able to cast it through terrain in order to help ganks (since Veigar isn't the type to run around the stage) and catch a channeler who's hanging in the backlines.
Heavy version of Baleful Strike. Suffers from being too situational. It's good against only a few kind of targets. The rest of the time it's lackluster.
1) Targets with low HP and/or Mana Resist. Since you only gain AP if you land the killing blow, you're pretty much forced to save it to use when they're obviously low, or you can instapop them. Also, the AP gain is pitiful.
2) Targets with huge mana pools. Also tends to overlap with targets with low HP. So they're doubly weak to Primordial Strike but at that point you're pretty much garunteed a kill anyway. Unless you're fighting a Tankgana, which has it's own problems (lol spell immunity)
If the target doesn't fall into one of these two categories, you're left with a heavy nuke on a large cooldown that only grants as much AP as Baleful Strike on a kill. At least Lion's Finger could hit people pretty far, Primordial Blast's range isn't good enough to get a kill. Finally, you have to stack a LOT of AP to make it effective late game. The alternative is to save it for opponents with large mana pools, assuming they didn't stack HP as well.
Proposal: Buff the damage. Rank 1 is all but useless and rank 2 only works well if you already have a ton of HP or you catch a caster who is low on health (and you're close enough to nuke them). Either remove the bonus to mana damage and raise the base damage, or up the mana damage to 50% and give the base damage a slight increase.= i rankes 1 and 2. Also, allow Veigar some time in order to reap the benefits of the AP bonus. Like, if the target dies within 5 seconds of behind hit by Primordial Strike, then Veigar gains such and such AP. If I recall correctly, it only gave 5 at level 3. Which is pretty sad for an ult. If Veigar isn't raking in the kills then it doesn't help at all. With the time delay, then a Veigar who isn't killing, but getting lots of assists will reap the benefits of the Ap bonus.
It's ****. Since Veigar is AP based, his passive should do far more for his playstyle. Give 0.1 AP per creep kill and 5 AP per champion kill like Pudge's Fleshheap. Or, increase Veigar's AP by 5 for 30 seconds after every spellcast (stacking). Or something as simple as "Veigar gains an additional 20-30% AP from items".
Vivi suffers from Silencer syndrome. Deadly in theory, squishy in practice. Yes, I've fed as Veigar, but I've also went 16-2 with him before. Buff Vivi, nerf Tristana.
(Disclaimer: All numbers proposed here are not to be taken seriously, the thought is what counts, the specifics can be ironed out later.)