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 not a spam build, just the build that works best for me.
Having RoA for extra HP, MP, and AP makes it a great item.
ArchAngels Staff increases your AP a lot and in the end your overload will be doing more damage than ever.
Void Staff is an extra bonus for the tanks that do have a lot of MR, but you could also just substitute it for something else like banshees, another staff, or will of ancients for some spell vamp.