Talk:V3.13/@comment-5238542-20131029231826/@comment-3974211-20131030153624

Early rank silence duration will actually have very little impact on gameplay - but are intended to improve his early game as compensation for slightly nerfing his mid game. At the moment, Kassadin's rarely use their Riftwalk for damage and solely to get in range of Q+E - the changes promote using the ability for damage, rather than simply position. It's risk-vs-rewards - Kassadins who now use their Riftwalk for damage are rewarded with mana refund and more damage, but are also on top of the enemy champion (and thus in a risky position). The reduced silence duration late game also means the enemy should be able to react while Kassadin is still in range.

tl;dr: They buffed his go-in and nerfed his go-out.