Completely agree with Spider-Dan. I use Shadowbind as a rank 30 Archer to stop rank 40 and up mobs. Because of Shadowbind, I was able to take Skeleton Swordbearers at rank 36 when I was 28 solo.

When in a party, Shadowbind can be used to incapacitate one mob while you strike down another (though this can be difficult to pull off with the current targeting system.) Me and my friend use a combo of Shadowbind and Repose to stop mob groups, allowing us to do higher quests without a tank.