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

Annie is silenced in the bottom, right-hand image, yet a silence is not mentioned in his abilities.

Given the high amounts of damage over time in his kit, maybe something like: "Vel'Koz's damaging abilities applies stacks on enemies hit per instant of damage. At 3 stacks, the target is silenced for a short duration. Stacks will not generate on the target while silenced."