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 my ap blitz build, made it for my brother, because blitzcrank is his main, and i wasnt satisfied with the ap builds on the website (no offense intended). I find that you can have tons of survivability while going full AP, so you do as much damage as possible while still being able to survive teamfights when you get focused (as you will). I only have 5 final items because for the last one it depends on the enemy team composition is and who (if any) are getting fed.
You can either go with if the enemy team has mostly AP champions, or if their ap champions are fed. The other item you can go with is if they're mostly AD/fed.