It's powerful, no doubt. I think it really shines best as a outlander, there are a ton of preps you would like to use when blind, and blindness is a real hassle. Even for a player that can run from pine forest to moudrillars blind, being able to see exits while blind is powerful. And its your best shot at hitting hidden thieves (something no outlander can usually see). It's really opponent dependent, if you are up against tons of necros shamans thieves and assassins its huge, also if you are a giant the danger of permalag to hiders can keep your pockets from being picked.