Why not give Veigar scaling AP Ratios?
With all the Veigar QQ at the moment, the main thing I've seen being complained about is that his laning phase is too strong and too safe. The obvious answer would be to just outright nerf his damage, but what if instead, his power was shifted later into the game? For example, his stun delay could be increased to about 1 second, then reduced by 0.1s per rank. His base mana costs could be made higher, but not increase with levels. Q's AP Ratio could be adjusted from 0.6 to 0.45/0.5/0.55/0.6/0.65, and a similar scaling could be added to Dark Matter.
The only thing I think doesn't need any tweaking is his ult, since that's kind of his defining ability, unless the Enemy AP ratio gets shifted to Veigar's own ratio.