One forseen problem with Morellonomicon
If this game really is balanced for the upper eschelon of players, the fact that top tier games have a much lower kill score might skew perception of how powerfull that 20% mana restore on kill/assist is.
On top of that, people who go to the pros for their builds might not use it at all; that passive just isn't going to be as useful to the pros. Granted, raw stats might be worthwhile for them, but then the passive is just icing on the cake for people on my level :D
