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.
While I usually leave Essence Flux to the end, if you're laning with/against someone who greatly benefits from attack speed, it's worth considering maxing it earlier.
You are EXTREMELY squishy, always stay at range, use Arcane Shift to get out of sticky situations, avoid getting hit at all as you don't have a lot of regen and always carry 2-3 hp pots. Mana regen runes means you can skip chalice and go straight onto dps items. Did I mention to stay way back?
Arcane shift and two escape summoner abilities gives us a bit of leeway to wait with grabbing upgraded boots, but if you feel they're needed earlier, do get them.
Grab Bloodrazor if you're having issues with high health champs.