quick feint questionFollow

Yes, it works while the tank still has aggro.

However, plenty of the more experienced people on these boards will tell you that it's a waste of energy, because there are better ways to manage your threat. On boss fights, one of the most important tactics is to use Vanish to wipe your threat part-way through the fight - after you do that, you should be able to DPS to your heart's content.

The real reason experienced raiding Rogues never Feint is because Feint scales horribly (if at all) with your gear, for instance when your Sinister Strike/Hemo start criting for 2k+, a Feint isn't worth anything.

best thing you can do is let your tank get a lot of threat first--and get blessing of salvation. by letting him get a head start, it'll maybe allow you to go all out for the duration of the fight at lower levels. when you start getting higher up the vanishing is a better idea. but really, let him get a bit of threat first and you might not even need to worry about it if your tank has great threat per second--get an addon called omen. you can watch the threat of other people who have it downloaded. you can see just where you stand against the tank.