Talewrite

Plate Armor of Etherealness

Armor (Half Plate Armor or Plate Armor), legendary, requires attunement · 2024 rules, SRD 5.2

While you're wearing this armor, you can take a Magic action and use a command word to gain the effect of the Etherealness spell. The spell ends immediately if you remove the armor or take a Magic action to repeat the command word. This property of the armor can't be used again until the next dawn.

Also in the 2014 rules (SRD 5.1).

This page includes material from the System Reference Document 5.2 ("SRD 5.2") by Wizards of the Coast LLC, licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/legalcode).