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.
Your general purpose Galio build normally though u wouldnt get to a stage in the game where u have all these items. When games end for me i usually still have my visage and chalice. I'll have either my banshees or thornmail (not both) completed no zhonya's and maybe the abyssal scepter but treads definitely completed. The aegis is completed after the visage unless the situation calls for more armor or my team mates need the survivability.