User blog comment:Emptylord/Leaked Champion: Vel'Koz/@comment-3974211-20140117015325/@comment-7709681-20140117021815

I mentioned that passive because was the first one that came to mine mind with such mechanic (Passive effect applied once per amount of casts), yet, there are other such as, ,  and.

It could be the first option that I mentioned aswell, since we don't know how short the cooldown of its abilities (Except Q) will be. :S