Armor of Intervention

Armor, (heavy), very rare

You gain a +1 bonus to AC while you are wearing this armor. Also while wearing it, any critical hit against you activates the magic with which this suit of armor is imbued. When activated, the armor does the following; it separates itself from you so that you are no longer wearing the armor, it casts the mage armor spell on you with a duration of 1 minute, and animates itself for 1 minute in the nearest unoccupied space next to you.

While animated, the armor is a Medium construct. Its AC is equal to what it normally grants its wearer and it has 30 hit points. The armor has immunity to poison and psychic damage and is immune to being charmed, frightened, paralyzed, petrified, poisoned and to suffering exhaustion. It has a flying speed (hover) of 30 feet. It makes two melee attacks with 5 feet reach, and a +6 bonus to its attack roll, dealing 1d10 bludgeoning damage on a hit. The armor acts on your turn and it obeys the commands you issue to it telepathically (no action required by you). If you give no commands, the armor takes no action. If the armor hits a creature, the creature has disadvantage on its attack rolls against you until the armor disappears.

The armor disappears when it drops to 0 hit points or when the duration ends, and it reappears on you, which means that you are once again wearing the armor.