Kassadin Ultimate Changes Idea
tl;dr Rift Walk gains charges as he cast, each charge costing additional mana and increasing in range and dmg.
So I've played a lot of kassadin since I started playing League back in 2011, and I know he's always in this weird state of balance, and I think riot does a great job in particular with never changing the feel of his kit and playstyle. My idea for the ultimate change instead of them just trying to find a range "ok now its good not op."
Rift Walk gains charges with each cast; each charge costing additional mana and increasing in range and dmg. (as of 5.4) base range 450 + 75x(stacks) I really think it adds good power to what he does well already, and even gives him some more strategic options, as well as leaving an open weakness for the enemy to play around I think also adding a visual effect per stack would be very nice also to give enemy's a notice "guys kass is getting stronger" something that looks like the jungle buffs, Molten shield, sunfire effect, etc. and just gets brighter per stack.