I main Viktor. I know only a few Viktor mains, at the start he's a little hard to master, but with practice he's soooo good. I don't know how I'll build him with the new runes, but I used to use:
vs AD: Magic Pen Reds, Armor Yellows, Cooldown per lvl or AP per lvl Blues, Flat AP Quints.
vs AP: Magic Pen Reds, HP per lvl Yellows, Cooldown per lvl or Flat Magic Res Blues, Flat AP Quints.
I really like when the ADC explodes with 1 combo lmao.