Not Updated For Current Season
To be completely honest, I just love to play Vik. I'm completely unranked, I started playing S6 after trying the game way back when it came out of beta and I sucked too bad to wanna play for a long time.
Viktor is probably one of my favourite champs to play because he just ****s out damage! You pop squishies and chunk tanks with you laser, your q is easy to kite with, your evolved w makes comboing and teamfights super simple and his ult melts anyone slow enough to get stuck in it's radius for too long.
He's simple to play and relatively quick to master as far as immobile mages go, topped only by Swain.
The only really iffy things for me with the masteries is Cookies vs. Assassin and Feast vs Double Edged Sword. The idea is to dominate with your damage since you won't be very safe until you have your first back items, a strong offense is the best defense and such. Assassin comes in real handy since you'll mostly be alone in the top lane, but the cookies may help with that extra bit of mana to finish off a low hp opponent. Also Feast does help with the laning, but 20 hp every 30 secs vs 2% extra damage... you won't have the **** tonne of damage that Vik is notorious for until later in the game and you'll be wanting any leg up you can get early in.
The entire idea behind this item build is to beef you up a little bit with ROA and have the energy shield from your q be as big as possible to soak up as much damage as you can. Seraphs has a backup shield for if you need it, Lichbanes and Thunderlords work beautifully together for some great burst damage. Sorcs are self explanitory, but the fun comes in deciding how you want to end the build. Personally I like Deathcap and Rylais. Zhonyas is for people who are scared of seeing the game through colourblind eyes for a short time and I like being able to hunt down the enemy back line and pop them. Protobelt helps with that sometime, Flash-Protodash-E-Q may as well be code for deletion on the enemy adc. If MR is the biggest hurdle in your game, the Voidstaff is there to back you up with that stupid 35% penetration.
I actually rarely play Viktor top since people dodge when they see it, but whenever I manage it I use that item core and it generally works out well. With the ROA stats it'll be harder to feed, Seraphs makes your Q shield pretty fat and unless you're being cc locked, you should be able to manage a kill or two in teamfights, assuming you don't get super lucky with a W-Ult combo in which case you can single handedly annihilate their team. My username on LoL is Kaladef