this dude have one of the lowest win rates, he has one of the lowest base damage compared to ap champions.
now some of u might say that he is a "counterpick". which is the main reason as to why he sucks. when a champion is ONLY viable when he is countering someone, that's a good indicator of a weak champion.
that's just like saying that aatrox before the buffs was op because he could win 6 matchups. same logic
Kazekiba2 votesKassadin's damage is nuts. His winrate is low because people dont know how/win to play with him or use his mobility to their advantage, or even build him correctly.
A tiny bit more base health wouldn't hurt, but Kassadin had to get an entire rune (Presence of Mind) reworked, so if he's weak then keep him that way. Champs shouldn't force the game to bend around them for everyone else 
Primaquarius1 voteslowest base damage
rework trundle1 votesop gg says 30 champions are worse than him, so a bit more than 20% of the champions
rawiazam11 votes[{quoted}](name=le un le seul,realm=NA,application-id=3ErqAdtq,discussion-id=Vdart1tk,comment-id=0001,timestamp=2018-03-14T18:08:45.115+0000)
op gg says 30 champions are worse than him, so a bit more than 20% of the champions
league of graphs says he is the 12th lowest
Schenix1 votesKassadin damage into mages and squishies is pretty high as the game goes on. He is one of the few champions who still scales linearly with game time and items and doesn't spike years earlier as well. If he got better base damages, then he is perfectly capable of turning online faster, which could be nice in this meta to be fair. However the health of that is debatable. The issue with him, is that if he does spike early, then his mobility may make him a monster that can control the game very well and make it almost frustrating for the enemy.