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.
With this build ive been doing quite well for last ~20 games or so. Just play safe and get your mejai stacks and you'll be unbeatable. Also, keeping ignite on cooldown at the start is a major factor on getting the minion kills and harrassing your opponents.
For the last item I usually go for even more AP. If i've been almost killed too many times, i'll consider something for the survivability, like banshee's veil or guardian angel.
I've also been playing around with the boots but mercury's seem to do their job best.
With a few mejai stacks rank 3 Tormented Soil is enough to kill minions so ranking Dark Binding up for maximum snare/damage. Black Shield at lvl3 is necessary to be able to avoid enemy stuns/slows/snares etc.