Vel'Koz's passive does not work with his design
http://i.gbc.tw/gb_img/s256x256/3077186.png
Vel'Koz was originally designed as a long range poke/siege champion. However his passive doesn't really fit that idea. A poke/siege character is supposed to be able to keep shooting Qs or whatever and slowly whittle enemies down. But Vel doesn't do that. A lot of his damage is stuffed into his passive, a passive that requires 3 hits in quick succession. Why on earth does a long range poke/siege champ have a passive that better fits a combo-oriented champion. Most Vel's just float up to someone, CC them and then press every spell at once to obliterate them. There's nothing pokey about that. If his passive could be changed to something that encourages the whole "we gotta engage before this Vel hits us with poke too many times!" then maybe he'd be a lot better at his job.