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.
Prepare for rediculous amounts of health and ability power, whole teams will fall before you
Magic Pen - Clear to see
Ability power - Always nice to have a small boost
CD Reduction - Needed to reduce pool timer and help with q and e spams
Health - Nice to give yourself a little more survivability off the bat.
If your doing great with no fall backs skip the spirit visage for another rylais crystal scepter. If you need magic resist skip a scepter for a banshees vail, make replacements where needed