Don't try it, Veigar is not a
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.
Threats to Veigar with this build
So i am writing this, because someone told me to do it. This build was testing with Final Boss Veigar and it is recommended to have this skin.
Ancient Coin, and Nomad's Medalion will let you earn gold, and regenerate mana. Morellocomicon, and Ionian Boots will give you max. CDR. Rabadon's Deathcap will make you much useful in team fights. Rylai's Crystal Scepter will slow enemies while chasing, or escaping, so you will help your team if you buy it. Last item depends on enemy team. If they have much HP, buy Liandry's Torment, it will even scale with Rylai' Crystal Scepter. If they have very big magic resistance, buy Void Staff. If they have Fizz, Fiddlestick, Katarina, or other champions with annoying ultimates, buy Zhonya's Hourglass.
In early game, hit enemies with your skills, to gain AP. Let your ADC farm, and you just use your skills on enemies. After level 3, you can do your combo: E, W, Q, and one normal hit, it will activate Thunderlord's Decree and maximize damage dealt. Remember to not use skills too much, because Veigar can easili run out of mana, and then be killed. You should always have at least mana for E, to stun enemies,and escape/let other teammate escape. Max W, because even if you don't have much AP, it will do reasonable damage. Use your ultimate skill on ADC, or APC, to kill them at the beginning of team fight.
Pros / Cons
The best ADC to playing with Veigar:
2. Miss Fortune
7. Kog' Mav
The worst ADC for Veigar are ADC's without any slow, stun, or snare, for example Sivir, Tristana, etc.
Initiate team fights. If you miss your E, go back, wait 8 seconds, and try to initiate again. Use your W, and Q to help with killing the Drake. If you have Rylai's Crystal Scepter, spam with your skills to slow enemies.
When your ADC is going back to base, stay at your lane. You can go back to base if you have 2400 gold. It is not that hard to stay at lane with Ancient Coin. when your ADC is not with you, try to kill minions with your Q, to gain AP. In middle game, when everyone are just going middle lane and fight, you can use W on ranged minions, to gain gold, and use Q on siege minions. Nobody will care about farming "support" in this minute.
Congratulations if you still reading this after so much grammar mistakes - I love you. So this build is really good, but you have to know, how to play Veigar. I accidentally discovered this build, and I played like 35 ranked games, and my win ratio is 74%. I know that this don't prove anything, but you should try it. It is really fun. And one more thing. Your attacks deal pure damage to buildings equal to 30%-40% your AP. So with 1000 AP you can destroy turret, or inhibitor with just 4-5 hits.
Good luck, and have fun playing this little, annoying champion ;)