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.
Whit this build you should play more agresive. You can start with a Doran's blade insteas of Meki pendant and buy it later in game but the mana regen is necessary. So you have to grab the stun first and if you lane with another charecter with stun it will be great. First blood is almost 100% yours. Have fun playing Sion. Thank you for reading!