The Nimzovich-Larsen attack: modern variation is rare and occurs in less than 1 in 100 games. From the data, you can expect that White will have a 50.39% chance of winning, while black should have a 49.61% chance of winning. Even though most players have probably never seen this opening, (so you can catch them off guard), the edge that White has is small (less than 2%). It is probably not worth it to study this variation, since as Black, the edge you gain isn't that great.