Mail of LuckArmor 13
Source Pathfinder Core Rulebook
Type Heavy
Price 2,600 gp
Weight 4 bulk
This suit of +2 resilient splint mail has a large, green gemstone inset in a prominent location.
Activate 
Envision
Frequency once per day
Trigger You are hit or critically hit with an attack, but damage hasn't been rolled yet
Effect You force the attacker to reroll the attack roll and use the worse result. This effect has the misfortune trait.
Activating the armor causes the gemstone to turn gray and become inert. You cannot activate the armor again until the stone returns to its original green color. The gem turns green again after 1 week or when a significant foe critically succeeds at an attack roll targeting you. (If an enemy rolls a critical success at an attack against you and you force the attacker to reroll that critical success, that critical success does not recharge the mail of luck.) Even if the armor's power returns before a week has elapsed, it can't be activated more than once per day.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
DivinationThe divination school of magic typically involves obtaining or transferring information, or predicting events.
InvestedA character can wear only 10 magical items that have the invested trait. None of the magical effects of the item apply if the character hasn't invested it, nor can it be activated, though the character still gains any normal benefits from wearing the physical item (like a hat keeping rain off their head).
MagicalSomething with the magical trait is imbued with magical energies not tied to a specific tradition of magic. A magical item radiates a magic aura infused with its dominant school of magic. Some items or effects are closely tied to a particular tradition of magic. In these cases, the item has the arcane, divine, occult, or primal trait instead of the magical trait. Any of these traits indicate that the item is magical.