So, I went from 134 to 138 in (literally) the blink of an eye.
It's called "The Scroll of Dark Rain"
At level 134, I'd finally amassed enough non-attribute XP to take magic D within 3 points of max. Then I handed over the scroll.
Holy crap: Fireworks, level lights, max skill message.
Oh, and 4 levels' worth of xp. =/
Anyway, I was left with like 1.5 billion xp, after having around 480 million. And then it hit me -- why not do that augmentation thing NOW? I am always getting into trouble with burden, carrying around too many arrow types, etc.
Of course, leave it to me to not have a SINGLE thing maxxed, and I'm off to augment. =P