This can be a very effective build late game for the over powered ability champion

The pros to this build is that late game your ultimate and lays waste can be an extremely good kill stealer and you are very strong with magic damage even when they do have magic resistance your archangels staff lets you you penetrate that.
The cons to this is that you can be squishy late game and will need to be very careful when going up with champions such as yi and lee sin as they can charge to you and afflict physical damage.