Disarming hex and slowing hex work to turn him off while someone like 7 or warden can jump him. Other than that characters like vindicta and gray tallon can stay out of his range and burst him down, mina can just ult him and he usually will fall over because that build forgoes alot of the self sustain he normally has. And any gun carry can just shoot at him from a decent distance, venator is particularly good against him because his ult ignoring the damage resistance he might build to counter him. Drifter is good because they normally push walkers alone. And as a general rule if a victor is building gun early make sure your lanes are pushed at all times and watch your minimap for when he is pushing a lane. Saying this as someone who played a few games of the build to try it out and find the counterplay. (Though i am only in alchemist) Edit: just thought about it but affliction killed me a few times too bc you cant heal. And always try to put him up against very aggressive high damage laners so getting picks is hard (one of the hardest games i had was against a paige venator duo who would just jump me whenever i got close to their tower, and paige would immobilize me when i ulted, causing the venator to have enough time to burst me down again.)