Straight from the Void and onto the Mid lane, finally Vel'Koz has been released! Before I get into the specifics of playing this new champion I want to make a few points about this guide. 1: I know that releasing a guide this soon after a champion's been released raises some questions as to the accuracy, but I'm hoping to not only get my input on this champion out into the community, but to also receive some input from other members. 2: I'm planning on publishing it immediately and working on it as the patches and strategies come out that way I can update the guide and hopefully keep the information relevant. I hope you find this helpful!
Vel'Koz is a ranged AP caster whose main damage comes from his burst, his passive Organic Deconstruction allows for a devastating amount of damage against anyone he targets, even most tanks have an issue when dealing with the damage from his burst. Personally, I feel like Xerath players would feel most at home with Vel'Koz considering the range and similarities from their kits and (in my opinion) their roles.

Pros:
Very strong teamfight champion
True damage passive
Strong laning phase
Ultra strong burst
Strong farmer
LASERS

Cons:
Squishy in most parts of the game
Dies relatively quickly if focused
Kit and burst take a bit to get used to
No reliable escape
Rule: 34

Relatively simple rune set, I prefer magic penetration to simple AP marks as it stacks very well with the true damage from Organic Deconstruction. Other than that I'd say that the defensive glyphs and seals are to make up for his Vel'Koz's early squishiness.

This is what your final build for Vel'Koz should look like, Athene's Unholy Grail is a great item for cooldowns and extra magic resist, not to mention that it makes the mana consumption from his burst less ridiculous. Sorcerer's Shoes is always necessary on any AP mid, there shouldn't be any reason why you're not building this. I will say that the Alacrity enchantment does make up a lot for how slow Vel'Koz is, though Homeguard might be just as viable in certain situations. Deathfire Grasp is a great late game item, not only dealing health based on enemy health, but increasing his damage output so on the off chance you're trying to take out the enemy tank this item is gonna be your bread and butter. Next, Rylai's Crystal Scepter it gives a great amount of health, increasing your survivability, and its passive is great for escaping from skirmishes and fights, letting you put your Void Rift down and slowing everyone who passes through it. Not to mention the added slow that this item can stack onto your Plasma Fission creating a 85% slow rather than the normal 70% making Vel'Koz even more effective at peeling for his team and helping to catch up to enemies in teamfights. Zhonya's Hourglass is also a strong item for Vel'Koz because of the extra 120 AP and armor Zhonya's will probably save your life from most AD champions while adding to your already strong burst. Finally, Rabadon's Deathcap is to give you a huge power spike in terms of your late game damage, as well as your full burst in teamfights.

Build Order:
I mentioned earlier that I would address which items to prioritize first, considering that Vel'Koz's kit is designed for long range artillery, much similar to Xerath, your defensive power really shouldn't be that high as you'll almost always be a safe distance away from most enemies. Your first item should be Athene's Unholy Grail not only is this item great for utility, 20% CDR, but your burst is going to benefit from the boost in mana regen increasing your survivability, as after you get this item you'll probably never run out of mana for the rest of the game. After you've built Athene's prioritize Sorcerer's Shoes, but don't buy an enchantment until later in the game as you'll need to decide if you want Homeguard or Alacrity depending on the flow of the game. Next, Rylai's Crystal Scepter normally Vel'Koz is squishy and extremely easy to take down if he's out of position or getting focused so the extra health from Rylai's will ensure that you have the slight tankyness that you need, especially considering his large hitbox. Your fourth item should be Zhonya's Hourglass, around now, you should be into the mid game, so the active as well as large AP from Zhonya's is going to help immensely in teamfights, provided you're at a close enough range to get focused from the enemy team. Second to last is Rabadon's Deathcap the gigantic power spike that you'll get from this item is going to make you a force for you team. Finally, finish off with Deathfire Grasp, now why do I finish with DFG? In all honesty you're not going to really need the extra burst that this item gets you until you're well into the late game, your active should be taking care of most enemies and the high AP from the other items should be keeping your power relevant, finishing with Deathfire Grasp allows for a strong boost of ability power, especially with Rabadon's, and the active, in my opinion, has most relevancy in the late game.

I see a lot of people put their first point Plasma Fission and try to max that skill first with Vel'Koz, this is wrong for a number of reasons. Plasma Fission is a difficult skillshot to land. Not just because minions can get in the way, but because its easy to dodge and the 90 degree split takes a while to get used to, not to mention its high cooldown compared to your other abilities. Void Rift on the other hand is an exceptional ability. Because of the stock system it utilizes even at level 1 Vel'Koz can still get his full burst damage out (provided the enemy is stupid enough to let themselves get hit that much). Next, Tectonic Disruption while the stun may not scale as you level the ability the cooldown reduction you'll be getting is incredibly useful and will allow you to lay down your stun/knockback multiple times in skirmishes and fights.
In all honesty, thanks to the damage on Organic Deconstruction you really don't NEED to level anything past the first point to still be relevant, but who doesn't like extra damage?

Most AP mids these days will almost always take Flash Ignite, considering how useful they are there's really no reason to not take one of these, although I will discuss some alternatives.

Maybe (situational):
Ghost Ghost is okay in terms of utility, allowing you to run away or reengage, but Flash is more useful.
Heal If you're against a strong poke lane and want a little extra sustain then I'd say heal is useful, though I wouldn't expect too many kills early on.
Barrier Considering your squishiness at nearly every point in the game, barrier could also be a viable choice.
Exhaust A great option for securing kills, although Ignite is more useful for this, Exhaust can be used to simplify landing your skillshots and Lifeform Disintegration Ray.
Teleport If you're against someone with heavy sustain (like Ahri or Gragas) then teleport would be a viable option, allowing you to get into lane quicker and giving you a global presence at all stages of the game.


Lol, No.:
Clarity His mana costs are extremely low, seriously, you should almost never be out of mana as Vel'Koz especially with once you get Chalice of Harmony.
Clairvoyance .......Really?
Revive Okay, taking revive is like saying you're going to feed, honestly as Vel'Koz you really shouldn't even be close enough to the enemy team to be taking fatal damage.
Smite Please don't run Vel'Koz jungle, he has no natural sustain and his ganks would be sloppy at best.