User blog comment:RoznosicielCiast/Is Siphoning Strike too strong?/@comment-5686533-20131105105303/@comment-9048637-20131106023109

Veigar doesn't get nearly as much out of farming his Q as Nasus. Sure, Veigar's AP improves all his abilities, but given how long his cooldowns are compared to Nasus' Q, that's not as great as it sounds. Plus, Veigar doesn't get nearly as much pushing power out of it - sure, he can melt minion waves kind of quickly with Dark Matter if they're clustered together, but so can Nasus with Spirit Fire and, if he's got it, Iceborn Gauntlet. Perhaps more to the point, Veigar is never going to be three-shotting turrets (unless the game goes on for, like, two hours or something).

There's also the fact that Veigar farms far more quickly off champion kills than he does off minions. I'm not trying to deny the importance of last-hitting minions with Veigar's Q, but the numbers simply mean that if you want to get anywhere fast, you have to be going for kills, not just farming all day. This has repurcussions for the champions' respective builds: whereas Nasus can go full tank (bar maybe one damage item depending on the situation) and still put out ungodly damage, Veigar still needs to build a fairly damagey kit if he wants to be useful any time remotely soon. In short, Nasus' Q is what turns him from your average bruiser to the 'full tank with carry damage' we know and respectively either love or hate. Veigar's Q really just makes him a fairly standard burst mage but on steroids.

Honestly, if you want to compare what Nasus gets out of farm to what another champion gets out of it, Sion is probably a better example. Give Sion an Atma's Impaler and the longer the match goes on, not only the tankier does he get but also the more damage does he do. In fact, I'd happily say that Sion probably gets even more out of farm than Nasus does; it's just that Sion requires some skill, both in building and playstyle, to avoid being kited all day with. But really, the guy's quite underplayed at the moment, I'd say.