Stats

Armor, magic resist, mana and attack speed are the same at every star level.

Veigar

1 star: Passive: Gain 50% more Ability Power from all sources. Active: Call down a storm of 12 meteors across the battlefield that deal 56 magic damage each. They can innately critically strike. For each one that kills an enemy, permanently gain 1 Ability Power. (Permanent Ability Power: ?%)
2 star: Passive: Gain 50% more Ability Power from all sources. Active: Call down a storm of 12 meteors across the battlefield that deal 84 magic damage each. They can innately critically strike. For each one that kills an enemy, permanently gain 1 Ability Power. (Permanent Ability Power: ?%)
3 star: Passive: Gain 50% more Ability Power from all sources. Active: Call down a storm of 24 meteors across the battlefield that deal 199 magic damage each. They can innately critically strike. For each one that kills an enemy, permanently gain 1 Ability Power. (Permanent Ability Power: ?%)