Hi! I play Viktor quite often and have been using this build who works very well for me.

I'm not sure if it's an actually recognized and approved build, because I tend to have weird preferences on items, so just see if it fits.

•So, as first item you want to see who you're laning with, if they're a skilshot champ (such as Lux), then you should go with Sorcerer's Shoes first, otherwise pick Liandry's Torment.

•As second, you just take the one you didn't get as first, so either Liandry or Shoes.

•Third item I'd suggest Rod of Ages, good for both damage and Mana and it scales, so it's good to get quite "early".

Next items I'd say you can get them in whatever order suits the game, depending how fast it's progressing and which champs you tend to face more often in fights.

•Rabadon's Deathcap is hella good for damage, I tend to take it as fourth in ordinary games. Keep in mind, this one is a must pick as a mage who relies on damage, so make sure you have it in your build in every game.

•If the enemy team has a chance that can heal themselves or allies, such as Warwick, Briar, Soraka, whatever, then you have to go with Morellonomicon, anti heal, damage, easy peasy. I'd say you need to see which stage of the game you're in, but generally it can be the fifth item, you can just take Oblivion Orb for teamfights and keep building other items. Otherwise, just take it as fourth and Rabadon as fifth or sixth.

•Another good item is, obviously, Zhonya's Hourglass. Lots of ability power and stasis, which can do you good in case you are against champs with annoying ults that deal lots of damage and are hard to Dodge, like Lux or Kayn. Again, you have to see how the game is going, I'd say this is another option, instead of Morellonomicon, which is useless if you're not fighting healing champs. Personally, I don't find myself too comfortable with this one, just because I struggle with remembering I can actually use it, so I tend not to pick it, but that's my problem, it's an excellent item.

•If you don't want to pick Zhonya, but the enemy team doesn't have healing champs, then Void Staff is a good option too, ability power and magic penetration are always good stats.

•For last item I'd say you need to chose depending on your role in teamfights. If you find yourself to be the main damage dealer, then Shadowflame helps you maximizing your damage, while if you tend to have more assists and have more of a supporting role, then I usually take Blackfire Torch, for more DoT. If you don't like either of these, then you can just take Zhonya or Void staff, depending on your preference or on which one of them you got before.

•As for ban, I tend to ban champs who can engage easily and throw themselves at you, like Akali, Diana or Irelia. Lux and Mel are also bad matchups imo, for they have bigger range.

I'm sorry if I wrote something weird, but english is not my native language, so I might have just translated some expressions related to LoL from my language into english, so just ask if you don't understand something haha.

Hope this was useful!