Hi I'm Majppo. (sorry for my english but... you will see :D)

I bring you some guide for low played tanky AP carry Viktor.
As first i have to tell you something: "Viktors passive isn't useless not even bad or disadvantageous"
He's the only one who can buy item with 100 AP and DoT bonus just for 1000 golds.

So, let's go to some tips, tricks, pros and cons.

I use this masteries becasue as AP carry u need lot of AP, magic pene, mana and mana regen.
Still if u want u can try way with 21/8/1 with MR,armor and HP but u need lot of mana and manaregen for early mid game.

Passive: Evolving Technology

Viktor starts with a Hex Core that provides him with stats and can be upgraded in the store to augment one of his abilities. The Hex Core can only be upgraded once, and cannot be sold back to the store.

Explanation:

U can buy one of 3 Augments.

Augment: Power
+3 Ability Power per level +220 Health +6 Health Regen per 5 seconds
Ability Augment: Power Transfer increases Viktor's Movement Speed by 30% for 3 seconds.


Augment: Gravity
+3 Ability Power per level +200 Mana +10% Cooldown Reduction +5 Mana Regen per 5 seconds
Ability Augment: Gravity Field has an additional 30% cast range.


Augment: Death
+3 Ability Power per level +45 Ability Power
Augment Ability: Death Ray sets fire to enemies, dealing 30% additional magic damage over 4 seconds.
Champion abilities

Q: Power Transfer

Viktor blasts an enemy unit dealing magic damage, returning a portion of the damage dealt as a shield.

Explanation:

45/50/55/60/65 Mana
9/8/7/6/5 sec Cooldown
600 range
Viktor blasts an enemy unit for 80/125/170/215/260 (+0.65 AP) magic damage, returning 40% of the damage dealt as a shield.

W: Gravity Field

Viktor conjures a gravitational imprisonment device, slowing all enemies by 28/32/36/40/44% of their Movement Speed and stacks every 0.5 seconds. At 3 stacks the target will be stunned for 1.5 seconds.

Explanation:

65 Mana
17/16/15/14/13 sec Cooldown
625 range
Viktor conjures a gravitational imprisonment device, slowing all enemies by 28/32/36/40/44% of their Movement Speed and stacks every 0.5 seconds. At 3 stacks the target will be stunned for 1.5 seconds.

E: Death Ray

Viktor uses his robotic arm to fire a chaos beam that cuts across the field in a lane, dealing damage to any opponenets struck in its path.

Explanation:

70/80/90/100/110 Mana
13/12/11/10/9 sec Cooldown
700 range
Viktor uses his robotic arm to fire a chaos beam that cuts across the field in a line, dealing 70/115/160/205/250 (+0.7 AP) magic damage to every enemy in its path.

R: Chaos Storm

Viktor conjures a singularity on the field which deals magic damage and briefly silences enemies. The singularity then does magic damage to all nearby enemies every second. Viktor can redirect the singularity.

Explanation:

125/175/225 Mana
120 sec Cooldown
700 range
Viktor conjures a singularity at the target location, dealing 150/250/350 (+0.55 AP) magic damage and silencing enemies in the area for 0.5 seconds. As it churns, it deals 40/60/80 (+0.2 AP) magic damage every second to nearby enemies for 7 seconds. The storm moves faster the closer it is to Viktor. Activating this ability again while the singularity is active will redirect it.

Viktor can control his lane really well but everyone have some Pros and Cons.

Pros:
High damage early and mid game with Augment: death
Great gank and team fight control with Gravity Field
Lot of HP and AP

Cons:
Little more demanding on gold farm
Easy to counter with high mobility champs like kassadin, tristana, ahri etc.

I can say just 2 things to my build.

1. You can start with Doran's Ring or with Boots and 3x Health Potion

2. Your last item is Will of the Ancients of if you have too tanky enemies then Deathfire Grasp

So, Early game with Viktor is just about farm and harass enemy with Death Ray.
Viktor have really great range and thats makes him dominate on his lane.
When you reach level 4 you are already ungankable with most of junglers because you have gravity field and most of junglers needs to come to you. You just place gravity field on your position and run from ganker.

Viktors mid game is about lot of damage and some surviability with his HP.
Now u can push lane and you don't have to worry about ganker. If you have some wards you can gank ganker first and then kill your lane enemy (Double kill for you). It's just about your accuracy with Death Ray and gravity field. Power transfer makes really great damage and gives you some shield and your ulti can kill two enemies at once. Viktor is just about your accuracy.

Late game with Viktor is really interesting.
You have about 3000 HP and 700 AP. You need to stay out of combat and try to do damage with your max range with Death Ray, if u have some luck and accuracy, you can hit a whole enemy team with single spell. In every team fight you will be a enemy main target so u have to save your flash to run away of team fight and pick kills from side. When is some enemy on half health now is the time of your ultimate. But don't forget "Use Death Ray and Power transfet on cooldown and still control team fight with gravity field!"
If you are succesfull, PENTA KILL FOR YOU!

Thanks to use my first guide, enjoy play with Viktor and leave me some comment please.

DON'T FORGET! VIKTOR IS ONE OF MOST POWERFULL AP CARRIES!