Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This was just a quick build I put together that has always served me well.
One thing I will tell you is Evelynn is a pretty unique character and not everyone will be successful with her. If you like to initiate battles and take on 2-3 dudes at once. GTFO.
First couple times you play her you will probably top the death chart but once you get the hang of her you won't be disappointed.