Karthus Related BUG Rylai's Crystal Scepter

1: Rylai's Crystal Scepter Does not work on karthus 100% of the time when dead, as his passive E, Q Ult does not proc the slow even though it has before 6.3. I swear it worked in 6.2 too.

2:You nerfed karthus's slow a bit back why was that? He has the winrate/pickrate of a galio and you let that happen?