Veigar is a ranged mage that farms for ability power also he is mana hunger,he is made too strong so he can take easy kills but he can die easily because of his low life also veigar has a very powerful stun that that can stun the hole opponent team and has dark matter so he can use it after his stun on the opponent target and he deals a big amount of damage to the opponent.

Veigar can have many types of runes Ability Power only but he can have Magic Penetration Ability power and Cooldown because one of them are taken for a reason Magic Penetration is for veigar to handle a tank as an opponent. Ability power is for all the game but more important for the early game for the farming. Cooldown is for team fights more or for escaping from powerfull opponents with Event Horizon (stun) or just for catch oponents and then kill them with your magic attacks or you can just use ability power runes only for a strong early game.

9 greater mark of insight for magic penetration
9 Greater Seal of Clarity for mana regen per 5 sec
9 Greater Glyph of Force for abillity power per level
3 Greater Quintessence of Potency for abillity power
or you can use:

9 Greater Mark of potency for ability power
9 Greater Seak of potency for ability power
9 Greater Glyph of potency for ability power
3 Greater Quintessence of potency for ability power

For Veigar there are many summoners spells that somebody can pick but one of them has to be an eascape spell like Flash Cleance Ghost or Echast also the second spell is better to be ignite, teleport or Ghost.First with ignite you can kills opponents with low life or you can beat them up more easily.Second with teleport you can get in and out of a lane or a fight in just 4 seconds.And third you can get close or away from a target quick with Ghost.

Veigar the tiny master of evil

veigar is a powerfull mage that you can play him to mid or to bot or top lane.Veigar's passive is Equilibrium:
Veigar's mana regen is increased by 0.5% for each 1% of mana missing.

first spell is Baleful Strike:

Active: Unleashes dark energy at target enemy dealing 80 / 125 / 170 / 215 / 260 (+60% of ability power) magic damage. If a target minion is killed, Veigar gains 1 ability power.
Passive: Veigar gains 1 / 2 / 3 / 4 / 5 ability power when he kills a champion from any source of damage.


second spell is Dark Matter:

After 1.2 seconds, dark matter falls from the sky to the target location, dealing 120 / 170 / 220 / 270 / 320 (+100% of ability power) magic damage.

third spell is Event Horizon:

Active: Veigar twists the edges of space around the target location for 3 seconds, stunning enemies who pass through the perimeter for 1.5 / 1.75 / 2 / 2.25 / 2.5 seconds.

Ultimate spell is Primordial Burst:

Blasts an enemy champion, dealing 250 / 375 / 500 (+100% of ability power) plus his target's AP in magic damage.

Early game
In early game with Veigar you have to start killing creeps with Baleful Strike so you can take ap that much so you can take easy kills in early game.Also don't use Dark matter and Event horizon in early game too much because they cost a lot of mana (use them only to take kill(be sure))

Mid game
In mid game with Veigar is power full enough to take kills easy but be careful because veigar can't kill two enemies together in mid game because his power is limited (exept if you have farmed too much and you have finished the most of your items and on of your opponent is mage you can be assisted by your ulty) there are possibilities

Late game
In late game veigar can kill 3 champions together in 4 seconds if you follow my built guide because of Event horizon and then you active Dark matter and at the end you can do Baleful Strike so you kill them one to one quickly and easily

Pros

cool buffs
small cooldown
powerfull magic attacs

Cons

anoing voice
slow
difficult playing
difficult to built

When you play like "ALL MID ATTACK" then you'll have to play team work you will attack with Event Horizon to the most weak then you'll do Dark Matter and after that Baleful Strike and if he is still alive do Deathfire grasp but if it's a tank you do again and again Baleful Strike so he wont have fife and then Deathfire grasp but if he has little life you'll do Primordial Burst.

Veigar in ranked game has to care more for gangs in early and mid game also in small lvl in ranked games where champions has runce equiped on them has more damage and more life or more ability power veigar is too easy to die so better don't try to go for first blood. Veigar in ranked games has to be more careful so in mid and late game can be better and can kill more champions alone.