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.
After playing 300+ game i've finally come up with the best sion build around.
Your early game is going to consist of harassing with stun while last hitting minions. Starting with saphire crystal and 2 health pots Pretty basic start for any champ (just watch your mana) around level 4 you can start comboing with shield/stun to do some decent dps. Remember to use your ignite around their half hp mark so you get the ap boost. You should be able to lane until the 1600 cash mark, at this point go back for your large rod.
By this point you should have or be very close to zhonyas around the level 8-10 mark, this is where you start to shine. Break off from your lane and start to gank the **** out of all lanes