EDIT: nevermind, it's just mislabled in the combat log as "concentration." It's the belt. I just noticed I haven't skilled concentration yet.
It's supposed to give +3 mana each round in combat. Now, when I first got it, I'm pretty sure it was working, but now it's not. I noticed the combat log only says +3 from concentration and +5 from rageeater, but zero from the belt. I even did the math in case it was just a logging error, and it's still not working.
I tried searching, but found nothing. Anyone know what the deal is?