Plate Armor of Etherealness
Armor,
Legendary
(requires attunement; cost 55000 gp)
Crafting Components
Efreeti breath bottled in a silver lined vessel
While wearing and attuned to this set of armor, once per dawn you can use an action to cast the etherealness spell. The spell lasts for 10 minutes, until the armor is removed, or until you use an action to end it.
Source