Add +3 to all saving throws and suffer 2 points of Eldritch damage every time you succeed on a saving throw.
The drawback to this cloak triggers even if its power was not responsible for the save’s success. E.g., if you needed to succeed on a DC 12 Will save and you rolled a natural 18, you would still take 2 Eldritch damage–even though you would have succeeded on the roll if you were not wearing this cloak.