I, I'm TheKirout and this is my first guide ever. I did a guide for Viktor because their is few here and he is REALLY underatted. Sorry for my bad english, I'm French

With Viktor, I take Ignite to do more damage, you can pick Barrier as well but viktor can shield himself with his "Q" so I think this is not that usefull plus, Viktor, for a mage, is not that squishy. But if you're scared and want to be sure to live or playing against Champions with big burst, Barrier can be usefull. I take flash as well because... why not take flash ? It's usefull to run away AND to chase.

First, I take doran+pots because Viktor is a mage and it's the best think to start with as a mage. I take the warding totem as well because you don't want to get bullied by the jungler, do you ? For the Hexcore (passive), I take the "E" one because I like to do a lot of damage with Viktor. But if you can't land your Death Ray you can take your "Q" item, this will make you run faster when you hit a Power Transfer. If you play him supp take the "Z" one to have more opportunity to stun and slow the ennemies (but I'm doing a mid Viktor guide, not a supp one).
Then the Sorcerer Boots are because it's pretty basic as a AP midlaner, you want more Magic Pen. The homeguard is here to come back to your lane faster so you can back with not that much of inconvenient. Liandry and Rylai are for slowing ennemies and, again, doing more damage. Rylai is usefull to make your opponents stay under your ult as well. Zhonya is for more durability. And Rabadon is for more damage again.

I take this Abilities in that order because the death ray is usefull for farming or doing damage. The power Transfer for using it on the ennemy then doing a bit of damage while your shield last. I max Gravity Last because it's just an utility so maxing it is not that usefull.
You can max you "Q" first if you have problem landing your skillshot.

Pros :
Goood damage.
He can stun and silence


Cons :
You need to land your skillshot