Faithless plate
Faithless Plate is a gear set that cannot be purchased through special shops like Purgatory Chains, Hell Forged or Twisted Earth gear, instead one must complete the quest: The Maiden and The Drunk. This quest can be found in Twisted Memories an end game map with a dark and twisted story.
To gain Faithless Plate, you will need to complete the quest: Nests Bones, in Twisted Memories which will grant you the quest item: Maidens Twisted Heart. With this item you can now enter Dungeons of the twisted maiden.
Here you can fight special monsters, once per week to gain loot either a mythic and three legendaries or just three legendaries.
Where Faithless Plate gear comes into place is if you have a full set of Twisted Earth gear equipped and you enter and manage to kill a creature or multiple as you work down the list, you can then have an increased chance to gain a piece of Faithless Plate gear as either mythic or legendary.
The chance works as such:
You roll a 1/100 and add 1% + number of level 400 items you have equipped (trinkets and ancestral items do not count).
If your total chance is higher then 80% you will get a piece of Faithless Plate gear.
Faithless Plate is on par with Delusional Silver and is the next upgrade after Twisted Earth.