Viktor
Now... I've played a lot of Viktor. This isn't just a mad person after being beaten by him.
His damage is very high, very reliable, and with long range. Whatever, that can be his niche.
I just think his W is way overbearing. It's cooldown is too low and it's duration is too high. It single-handedly wins teamfights and a non-ultimate ability really shouldn't be doing that. With 25% CDR it is up over 40% of the time and it makes it impossible to get to the back line.
I really think this needs to be looked at.