Hello, my Name's Elwormo and this is my first guide i made.
I want to share my personal prefered Veigar build with you.

In this guide, you can get over 1000 AP with Veigar, but only if you stack your q very well,
I'll talk about the earlygame farming and I'll give you some tricks and tips for how to pwn with Veigar.
I won't talk about my runes and masteries, because there are alot of declarations about it.

Farming is very important. If you don't farm enough, you won't have enough to solve my build, because it's very expansive.
Firtly you want to make sure to lasthit the minions with your "q".
Secondly you shouldn't use the other spells until level 6, otherwise you'll be out of mana. --> If the enemy midlane Champ attacks you, just dodge it and let him push. Just make sure that you are in the Exp range and that you can farm with your q.
Before you reach level 6, ask your jungler to gank. This will help you to make a 99% Kill.
When you reached the 6th level, take the manapot and prepare to attack the enemy midchamp.
Cage the Enemy with your "e". Then place your "w" a little bit behind the enemy and hit him with your "r", ignite and "q". This should be normally enough to get your first kill.
Port back and buy "kage's lucky prick" and some shoes. If you have some Gold over, buy a Health and Manapot (eventually wards too).

If it's possible for the jungler, tkae with him the bluebuff, it'll help you in multiple ways (Mana Reg. + Cooldown reduction)

When it comes to and teamfight, make sure that you are behind your teammates. If you see the change to cage someone, do it and land some "w" and "q" on him. Normally the team will finish him up and it will garant you an assist/kill. If attacking an tank/offtank make sure to land your "deathfire grasp" first, because it does alot of dmg. Cage your enemy and land your "w" and "q" on him.
If attacking an AP/ADcarry/Supporter, make sure to hold distance. They'll kill you in notime. Cage them and land your "w","r" ignite and "q" on them. They should die instantly. After killing them make sure to return to your teammates, because u wont have a chance if someone attacks you after you killed somebody (all spells are on cooldown).

Thanks for reading my guide. Please leave a comment below about the +/- in my guide and what i should do better
I hope you'll have some fun with veigar :)