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 WILL NOT MAKE YOU A GOD!
To start off, you will have tons of mana to never worry, so much magic pen that magic resist becomes almost useless, and a crazy amount of damage with your ice blast.
The main focus here is to, of course, maximize the damage of ice blast and your ult. You CAN switch up items like say, a mejai's or more archangels. The way to get maxed out AP is all archangels, but that is another story for another time. Early game you should be able to get FB if you have a good partner. Solo mid is possible with your crazy ice blast damage and consume.
Focus on harassment, try to only ice blast when your passive is active, unless you really need to. Work with your partner to get FB or a kill. Consume will allow you to lane almost forever, alongside your health and mana pots. stay in lane until you can get tear and at least your base boots.
MID GAME- Start assisting other lanes or continue to push yours, try to gank as your slow will greatly help others chase the target, as well as you. Make sure you have zhonya's pretty quickly, as it will greatly increase your damage output. Lich Bane will improve your killing, after an ice blast you almost get a second one on your next attack, and with it's low CD you can spam it nicely.
LATE GAME- This is when you should be running into team fights, ulting, and killing everybody. Once you get your archangels your AP should skyrocket if you have been spamming your skills. Void Staff will give you enough magic pen alongside your mastery and boots, so the final item is really up to you.
To wrap it up, you are a killing machine. Use Ice Blast, get a Lich Bane attack, Ice Blast again, dead. You will also be somewhat tanky that you can take more than one hit. Very nice for a powerful mage like yourself. Golem is AMAZING to have, it will make your abilities have almost no CD, and you will never run out of mana, not that you should anyway. Go out, have fun, freeze some ***es off!