good veigar ap build.
early game:farm exp and gold dealing last hits with baleful strike.
mid game:push and gank!aim ganking mages with ultimate.
late game:push, gank, help teammates, win!
sorcerres shoes: a good start.movement speed and a little spell pen.
void staff:ap and more spell penetration.
will of ancients,hextech gunblade:ap and lots of spell vamp.
zhonyas ring: lots of ap, ap, ap and even more ap!
rylai's cristal scepter:slow with spells hp and ap again!
ap, max mana, mana reg, cooldown reduction are great masteries for mages like veigar.
magic pen, mana regen and AP runes are great.
baleful strike:good damage and ap farming
dark matter:good creep killer,great combo with event horizon
event horiszon:detects enemies from bush and stuns.
Primordial Burst (ultimate):great mage slayer,lots of damage if target has ap build.
combo: veigar has just one combo but good.
event horizon then baleful strike then dark matter.if enemy has low health u can use ultimate.