User blog comment:Grrrbear26/Kassadin is broken, and I have the glue!/@comment-6061249-20150207084107

IMO Kassadin needs an entire rework. You can't have that much mobility on any champion really, since whatever you put into other abilities, the mobility will always make things different than expected. In fact, most of champions in game that have really good mobility will always struggle between being too strong and too weak (really, put there anything, Riven, LeBlanc, Kassadin, Ahri, anything... Maybe, but MAYBE Zed is an exception), and champions with poor movement and not much things to build up for it will stay unpopular.

Mobility always makes a huge impact on balance and cannot be fixed by switching numbers.