Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Basically, Veigar is a nuker. You don't have a lot of armor, so if you get piled you're pretty much dead, but you do have an amazing stun which you use to your advantage... ALWAYS, whether its getting away, or chasing someone, if you are chasing, flash + stun = ownage then you just nuke the hell outa them and put on ignite if you aren't to sure they're gonna die. Also, with veigar, his "Q" spell means you want to last hit minions, the more last hitting, the stronger you'll be, and the more nuking you can do >:) Also you'll gain ability power for killing enemy champions, so eventually you'll pile up a ton of mana and ability power, then nothing will be able to stop you.... unless you get piled >:(
At the end of this build, you'll have about 1.2k ability power, though its very expensive, you'll only get about 600-800 each game :3
Credit goes to ArKoniK for showing me this build, thanks :)