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 is a heim build that tries to reach the late game.
You will want middle lane, but it not 100% necessary.
At the beginning you buy the Amplifying Tomb and the mp pot, if you believe that the middle lane will be a DPS with longer range than you, or if you seem to take a lot of hits from the person, you can switch it out with a hp pot. The first time you b you should have enough money to buy a sorcerer's boots and then teleport back to your lane. If your opponent seems to be getting ganks on you, play more carefully and or use more grenades.
Mid game your lucky picks should be stacking up and so should your cash after you get your last one. You can choose to switch to a deathfire if you need the AP, MP regen + active ability early, if not save up to buy the archangel's staff (and sell a kage's pick) so you can get higher MP, better mp regen than the deathfire and in the end, more AP than the deathfire grasp. Rinse and repeat for the other items, and void staff and rylai's are interchangeable as you might need more hp if you find your too squishy, or can't finish or ganks and void staff if you find you aren't doing enough damage, but by this time the game should be over or close to. Most late game items are interchangeable depending on the situation.