Vel'Koz; A Small Buff
Vel'Koz is pretty balanced and strong at the moment, so having even a post like this to suggest a buff is really weird. Vel'Koz is one of the only champions that require mechanics to play because of his Q+W and E+W combos (ultimate is a follow up tool, no mechanics required) on top of a lot small skill values Vel'Koz. So basically Vel'Koz is indeed strong, but his skill level almost does not match up with the reward he gets from it and feels like it is better off just playing an easier to play champion that has an equal (or even greater) rewards to them.
So my idea will be increasing his DPS, aka this is a late game buff towards helping him kill tanks since he struggles too much in tank busting. A DPS buff can happen since it does not increase his power towards disintegrating squishies, but helps him fulfill the role of a damage dealing, immobile mage of killing the tank line in the late game. Giving a numerical damage buff will just make him over the top and would require an immediate revert.
The buff is a reward for the skill play and adding on to his cool feature which is his passive; Vel'Koz across the kit is a super cool and unique champion which has very good kit synergy, he is a very well designed champion - good job to his lead champion designer.
Additional effect to Organic Destruction (Passive): Every 3 stacks of Organic Destruction will lower the cooldown of Plasma Fission, Tectonic Disruption, and recharge time of the current charge of Void Rift by 1/2/3 seconds [ranks @levels 1/7/13].
This is an additional effect, it still does the true damage, but additionally with dealing true damage the cooldown and recharge time of his basic spells will goes down slightly. There will be a hidden 0.5 second cooldown, meaning the effect can only occur one time per using a spell combo and prevent basic spells refreshing by procing the passive on like 5 or more targets at a time so the cooldown reduction and recharge time reduction is the same whether 20 units or 1 unit took true damage from Organic Destruction. So this is only useful when trying to kill tanks in the late game because less cooldown and charge times on spells mean you can take down high health and resistance targets because more spell rotations and does not make Vel'Koz over the top with killing squishies faster, but still give Vel'Koz late game damage for tank busty with the same burst value he has now to not effect other targets or more power earlier in the game in that sense.