An Idea to nerf Kassadin, but also return his bases to a reasonable number.
TL;DR - His damage is absolutely not the problem right now so stop pretending like it is. Fix his insane lategame snowballing and teamfight pressure and revive his damages to an actually reasonable scale
Now I shall begin.
Kassadin has always been a frustrating champion to balance due to his intense snowballing and teamfight presence; being able to continue chasing and slowing enemies even when getting an incredible distance away. Kassadin gapcloses with 700 units using riftwalk and then uses force pulse, having a 700 unit cone; this very simple combo covers 1400 units instantly. A common complaint nowadays though is that Kassadin's damage is just outright lacking, and just for his long history of being perceived OP, Riot has been pretty trigger happy to slap on another nerf that isn't supporting the real issue to keep him in check. This has left his damage butchered, but regardless of it, in a perfectly set up teamfight, he can still devastate the enemy team. Riot has pretty much ran out of reasons to keep cutting his damage, so it's time to cut his utility so that he can actually have decent base damage and have it be on a more fair level.
From my point-of-view, here's what I would like to see for Kassadin to nerf his godlike teamfight pressure, but also give him the damage he deserves when being scaled/leveled.
Kassadin does not have lockdown utility. The only thing is that Kassadin can always continue to deal his damage very effectively with his constant giant gapclosers. Kassadin should still however be deserving of snowballing and dealing actual meaningful damage when appropriately played.
(Basically lower utility to increase damage, but also not have it to be able to repeat until everyone cant do anything at all about it)
Movement speed increased to 345 from 340
Attack speed per level reduced to 2.5 from 3.7
Mana per level reduced to 62 from 70
Null Sphere: Damage - 80/105/130/155/180 > 80/120/160/200/240 Cooldown changed to 11 from 9 Shield duration now lasts 2 seconds from 1.5 (shield value unchanged)
Nether Blade: Damage - 40/65/90/115/140> 40/70/100/130/160 Passive damage is now 20/25/30/35/40 from 20 at all ranks Cooldown changed to 6 seconds from 9
Force Pulse: : Damage - 80/105/130/155/180 > 80/110/140/170/200 Cooldown changed to 12 seconds from 6 Kassadin no longer needs to stack charges to use Force pulse. Mana cost changed to 70/80/90/100/110 from 80 at all ranks Slow duration increased to 1.5 seconds from 1 Slow percentage changed to 38/46/54/62/70 from 50/60/70/80/90 Kassadin now gains an attack speed buff of 30/35/40/45/50 for 4 seconds Active sound effect moved to the attack speed duration Sound effect speed slightly increased
Riftwalk: Range changed to **600/650/700 **from 700 at all ranks Cooldown changed to 6/5/4 from 7/5/3
Cooldown for mana to reset to 75 reduced to 15 from 20
Riftwalk's cooldown is now unchanged from cooldown reduction
From these changes, this will make Kassadin stay in melee range during the fight to keep participating in the fight. It's either that, or he's punished for a long time to wait for cooldowns to join in again. He will be able to waveclear easier in lane, but with his CD doubling in teamfights, Kass needs to rely on his attack speed boost to continue being effective in the fight, thus putting himself at a reasonable risk to continue doing damage.
Now at the end of all this, the values end up being unchanged, but the biggest part to this is that he will not have access to the same utility until level 16, and even then, he wont be able to just spam everything away in a teamfight to just heavily clean house. but even then again, he will have reasonable bases to have a decent innate start to fighting.
Please leave constructive criticism and feedback on what you think about these changes. It's supposed to be a nerf and buff and the same time, but moreso a nerf to being able to chase and ace.