Each Sanctified item has perfect stats, like an Ancient Legendary item, and in addition to its usual Legendary ability it has one of the three class based powers. The major new mechanic, Sanctified items, requires you to find an Angelic Cruicble in game - they can only be found once you are level 70, and they can only be used on Equippable, not Crafted legendary items. The basics for Season 27 are not especially complex. Well, for starters, you can look here at a list of all of them.

So, how do you decide which Class has the Sanctified powers you want to play around with? Since each class gets three potential new powers and you can only equip one Sanctified legendary item at a time (but you can have as many in your bags/stash as you want) it will be possible to have specific builds using different Sanctified legendary items, and thus tapping into one of the three Sanctified powers available to your class. Season 27 adds the new Sanctified mechanic, letting you upgrade legendaries with the Sanctified designation using an Angelic Crucible, giving them the perfect stats of an Ancient Legendary, the usual legendary powers, and a new Sanctified power. The choice of which class to play in a Diablo 3 Season ultimately comes down to what you’ll have the most fun playing.

Diablo 3 season 15 icy veins