Veigar is actually an extremely broken champion. His weekness is the early game, and his strength is the insane amount of damage he can deal in the mid/late game + his cc with e. Excelent teamfighter, and a champion that can hypercarry 1v9 easily.If a veigar gets fed, it's a gg.

pros:
-insane late game
-insane damage, even without feed
-great teamfight cc with e
-can one shot
-hypercarry
cons:
-very squishy
-kinda expensive build
-weak early game