"I, Veigar, will knock you all down!"
"YOU are error!"
"This isn't even my final form!"
"What is a champion? A miserable pile of pixels!"
"All the cake is GONE!"
"Hey, LISTEN!"
"My power is OVER"-- Actually, we all knew this one was going to be there... Man, he is a walking, talking reference machine.
Also, pronunciation of Veigar confirmed as "Vay-gar."