Kasssdin doesn't seem strong to me, even when is fed or has Riftwalk stacks up. I used to play Kass back in the day, and I know he has a spell sheild, but I still own him as Mord in lane.
Why is everyone saying he's strong? I don't get it
It seems like the issue with Kassadin just revolves around people not being able to punish his early and mid-game and close the game quickly. He has negative damage before at least two items so if you're not bad you should be able to deal with him easily. I mean a lot of champions have ridiculous gap closers and damage - ehem, ehem, Yasuo, Pyke, Akali, Fizz, Katarina and Yi (to a lesser extent) - and their early to mid game is also decent.
well i mean if a 2/4 kass can gap close then 100 to 0 a 15/0 adc in the blink of an eye, then we got problems. people are complaining about akali and irelia, but at least those two have restriction. akali needs land her skill shots and irelia needs targets to dash onto to gap close. what about kass? kass just go where ever he pleases.
Because of teamfight and chase potential... Stacked Riftwalk will delete any backline.
Um... its because if he survives to 25-30 mins and gets 2 items he shouldn't be able to fucking destroy everyone and just delete people with his dmg and mobility.
and 
are just as bad but are good at all phases of the game while 
is weak as shit early and is entirely dependent on having a a team that doesn't suck before he can even play league of legends. Picking Kass is a gamble that your team will get to late game. He gets zoned out of farm by anything with more range, and because he's hard to gank, the enemy jg spends more time ganking the sides. He has no hard CC so your team will need to pick it up somewhere.
If a player is getting just even farm with Kassadin and avoiding poke, he's probably fairly good at that champ. If he's going in for trades/running electrocute - watch out - he's an exceptional kass player because the trades don't come as free as they are for other cheap/ranged shit running electrocute mid.
Cause he is strong, but he doesn't need nerfs.
A lot worse heroes, that are a lot stronger early and late, with a lot more faceroll and less costs for their strength.
New Akali is literally more mobile than kass whilst having 0 mana costs.
He is also very high risk, you gotta get right in their face as a pretty squishy hero tbh.
I literally tried to chase her with 0 stack riftwalk, flash and ghost and I couldn't catch her....I mean...that's just unreal dude, I even had like level 2 riftwalk and about 30-40% cdr.
but I still own him as Mord in lane.
Iron 2 doesn't count. You just fought a seriously shitty Kassadin player.
52% wiinrate 3,50% playrate as well..
