Can we give Kassadin some relevance ingame?
Something based on his E stack passive. In other words, he could have a passive that states, " Kassadin gains empowered spells based on number of spells cast".
Q - Like a fully stacked Q allows it to bounce up to 3 times (Shield remains the same). W - Stacked W allows more mana regen'd (or sth idk) E - Same mechanic (idk) R - Original riftwalk range.
To make it more obvious, Kass can glow when he's fully empowered. Also his icon could change (similar to Kha'Zix/Rengar evolved/empowered icons)
So what it means is that Kassadin can be Kassadin but only at specific periods. He can still skirt around fights at his insane range but once he does it once, he's gotta cast a lot of spells/ be surrounded by someone who does to be able to do it as effectively again.