Hey guys im really into mobile champions that can do alot of damage( i have 
,kassadin seams to fit this profile perfectly.Ive heard from the general public that kassadin is weak ,but the few kassadin mains i know swear by him and always wreck with him ( i have a silver kassadin main freind that beat a platinum ahri ) .Ive seen him wreck on stream and in games.So whats the deal with everyone saying hes weak?
Kassadin is currently a minion at the moment.
He is weak low damage high cd not good ratios
Kassadin is a hard snowball champ that relies on not just winning lane, but doing so in a fashion where he is ahead of the entire game. The issue with this is that he is melee, in the mid lane. A lot of matchups just make his life a pain that are popular. So what he generally ends up having to do is to farm and survive mid, then get fed off roams or jungle ganks. His damage is good as long as he has an item advantage.
Major cons to him though: 100% snowball reliant, can lose an entire game just because you face an equally skilled or even slightly less skilled player on a champ he struggles vs. High skill floor, takes a lot of knowledge to pull him off at all. (breaks 50% winrate with people who have played over like 80 games on him, but is sub 45% before that) Games rarely go long enough for him to reach his potential late game if you didn't snowball super hard early (breaks 50% winrate at 40+ mins).
He is a rather risky champ to pick up in his current state, the risk does not match the reward of dedicating yourself to learning him. Just as easily put more time into Ahri, or Fizz, and get better results.
Of course if he is ever buffed to be "viable" he will become a terror in the hands that spent the time working with him now. So really up to you if you want to work off that.
he's not "unviable" but you're going to have to put in effort to prevent him from feeding. A fed Kassadin is scary, but half the time he only has half a passive, and he is very easy to dumpster early game. Azir is one such person. Anyone with range, really.
Kassadin is viable, but he is currently on the weak side due to his mobility being cut and his base level 18 stats not compensating for his weakness after the AP items were altered.
