Thanks man, indeed E costs alot of mana, however I think it's still better to have it with much damages than having the Z with some percents more :p
Z is one of these abilities you get one point in and then max it last for me. But, you could do it if you want, it doesn't change anything.

Thanks for your reply :D

great guide,i would max out W first cause E now costs too much mana for the low dmg it deals but otherwise this guide is perfect