Last Stand Armor

From Explorer's Guide to Wildemount, page 267.

Description
Armor (any), very rare.

You gain a +1 bonus to AC while wearing this armor, which shimmers softly.

If you die while wearing this armor, it is destroyed, and each celestial, fey, and fiend within 30 feet of you must succeed on a DC 15 Charisma saving throw or be banished to its home plane of existence, unless it is already there.