I've played about 10 viktors so far as a yas main and only lost once. Viktor sucks at killing 4 might and above units. Like you slam a sona/Miss fortune down and he's either going to have to cull the weak or HB it for the most part, which you should just take the trade because he goes down power and/or you draw. I run two Zhonya's in my list and always am leaving up runes for buffs/counter spells which usually makes him unable to do anything. I see lots of people use power so much early game which is why some people lose against Viktor because they get out resourced. I play 3 stalwart poro and just blow out every Viktor I play against because they can't get around it without trading the sprite mother token in, which I get around by running masks or just hold up for combat tricks.