The difference between Veigar back then and Veigar now.
I think the main difference people have to look out for between Veigar back when he recently got nerfed and Veigar now is the items he can buy. The mage item rework and Zeke's Herald rework probably benefited him more than Riot assumed. I am pretty sure mages generally get AP faster before because of Needlessly Large Rod's cost. I don't know much but I am thinking the AP item changes was a big part of it. I'm not saying nerf AP items because that's stupid. I'm simply stating that he might be "OP" because of item changes.
What do you guys think?