Pro's

* Spammable Q
* Skills are versatile for escape
* Death Ray can be used while fleeing
* Unlimited amount of harassment

Con's

* Squishy
* Primary target
* Skills need time getting used to
* Ultimate on long CD

I chose the simple normal mage runes (in my opinion) aiming for Magic Penetration Marks, Mana regen per level Seals, Cooldown Glyphs, and straight Ability Power Quint for some early AP.

Since you can easily spam your Q, I chose to level it up by level 9, and your Death Ray and Gravity field can be level up based on your standards. More damage output go for the Death Ray, but if you want a stronger slow then go for gravity field. Of course you level up your ult as soon as you can, at levels 6, 11, and 16.

Viktor is a very mana dependent champion, but his spells are quite simple to choose. Ghost helps you chase down harder and to escape much more efficient and ignite more or less ensures the kills.

Ghost - Yes
Ignite - Yes
Flash- Sure
Teleport - Sure
Clairvoyance - Leave it to the support
Revive - No...not a good idea
Clarity - Sure. Good early game spamming and late game sustainability
Promote - Leave to support
Smite - you crazy..? No
Cleanse - Ehh not necessary as you can escape ganks using gravity field
Fortify - Leave to support
Heal - If you want, not a big fan of it.
Rally - No
Surge - In the middle. More AP for bursting

Starting Off

As a mage, you have quite limited choices as far as starting items go. You could go for Amplifying Tome if you want some extra AP, or you could the standard Doran's Ring. If you want a head start on spamming spells then Sapphire Crystal would be a good idea. It all depends on your personal play style. I personally prefer the Doran's Ring because if gives you a bit of what you want, health, mana regen, and some AP. After that try to stay in lane and farm as best as you can till you have 350 gold to purchase your boots, then go for your Catalyst.

Mid Game

You hear a lot about how important mid game is to a player. Here is when most of the ganks and kills are happening and most of the gold is being earned. Here you want to get your Rod of Ages quickly so you can max it out as quick as possible. Finish off your sorcerers boots and purchase whichever Augment item you wan (I personally like using power).

Late Game

Here is when the magic happens, when your AP starts to drastically increase and you start to annihilate enemy teams (Viktor is a late game type champion so this far in the game he should be tearing people apart. After your Augment item, you might need some extra health and AP so go for Rylai's Crystal Sceptor, then Rabadon's Deathcap for added AP and last you would want Void Staff for those champions that are picking up some magic resistance. This last item can differ from player to player as some prefer to get Abyssal Scepter due to its magic resistance. Whichever one works for you go ahead and buy. Another good last item would be Morello's Evil Tome or even Will of Ancients so you stay a live more.

The Snow Ball Item

Most experienced players have heard of the casual snowball items such as Sword of the Occult and Mejai's Soulstealer. Mejai's is a very good item to purchase if you're very experienced and you know you'll pick up kills without dieing much whatsoever. Personally, I'm not into snowball items as the risk is far greater than the gain, but if you're up to getting it, by all means go ahead.

Viktor can be considered a nuke for how much damage he can put on instantly on a champion. It's wiser to go the solo lane in Treeline or to take mid in Rift. In treeline, you want to harass, harass, harass. Don't give yout opponent a chance to farm or get close. The more you farm the better, and try to coodinate with your teammates on bot to gank top or even you go bot to gank when you get your gravity field at level 4. In rift, do the same and harass, but not so much where you'll waste all of your mana quick. Just play smart. On ganks, lay down your gravity shield in front of them in order to either force them a certain way or for them to walk through and get stunned. Then if you get the stun, place ult, chase and spam Q. This should be easier once you get your Augment: Power item which gives you the movement speed boost when you use your Q.

Remember...YOU'RE THE BURST AP! You're job is to NOT initiate but to rather sit back and pound on them. A lot of people think that because you have some decent HP you can initiate but their absolutely wrong. Yes you'll be better off dealing with damage but not to the degree that you can take so much of it.

Also remember that in the case you get near running out of mana, make sure you have enough to at least cast your Gravity Field..or, if you have your Augment: Power and Rylai's, your power transfer.

Make sure to place your ultimate in a place in can be effective due to its long cooldown. Don't use it on any one champion because you think you can pick off the kill (only do that if your quite skilled with him). Your ultimate is best when you use it on 2+ champions bundled up. It's an AEO (area of effect) spell so it'll damage all champions it's on, also that 0.5 second silence can be a great use in team fights.