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 is my first guide, however don't be lenient. I want to see honest critism. On introductions I'm gonna just tell you all - Mejai Soulstealer is not more useful than last (third) Archangel Staff. It's a difference of ~50AP (yes, that's right you'll get additionally cooldown reduction, but it isn't easy to stack if your team is weak.
(I will expand my guide later)