Its only 6 ticks. 36 seconds. And, really, it doesn't lower agro by much. Chances are, if you're going to get agro, this won't stop it. Still, it'd have been nice if it were a longer duration, then it could be included in your buff-up preparations for a hunt. Or, if it were more than 5% off agro, then you could cast it on yourself before opening up a series of nukes.
In this spell's current state, its not very useful. And, keep in mind, its a 24-second recast time. This means that, if you don't want to waste a slot on it, but only switch to it quickly when you'll need it, it'll take 24 seconds for you to be able to cast it, after you find it in your book and mem it.
Sorta ruins my hopes of this thing.
Edited, Mon Jan 16 04:21:42 2006