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.
Full mejais stacks, max mana on each archangels, at full builds its more like 1.3k ap.
Mostly an estimate, not sure exactly. But its more than 1.1k ap. This makes ryze squishy, because you have no hp from items such as rylais, that most people get anyways. but this is an all out nuke. you for the most part can 1v1 tanks and still faceroll them.