The Spiked Armor can be found in Sword Coast Adventurer’s Guide, page 121.
You have a +1 bonus to AC while wearing this armor, which shimmers softly.
If you die while wearing the 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.
Spiked armor is a rare type of medium armor made by dwarves. It consists of a leather coat and leggings covered with spikes that are usually made of metal.
The wearer has Disadvantage on Dexterity (Stealth) checks.