Most of you who play locks learned very quickly that it's taboo to EVER use fear in instances, no matter how desperate you might be. When an enemy is feared, it loses control and often runs right into a group of its friends and they all join in the battle. So the situation goes from bad to impossible. It's about the easiest way for a lock to get chewed out and booted from a group too.
But I found a way to use fear safely in an instance, even in reasonably close quarters. By doing this, a lock can solo an enemy without being touched. This can be really useful when there are just too many enemies to deal with. This technique is possible with any spec, but affliction spec makes it much easier. With about 21 points in affliction you learn curse of exhaustion which slows enemy movement by 30% making them MUCH more manageable.
When you have an enemy you need to take care of, back up and get him to aggro onto you. If you can, use curse of exhaustion. Have him chase you as far back from the other enemies as you safely can. When he gets too close, fear him. He will run around randomly. Now this is the key, watch him closely. When he's getting too close to any other enemies, immediately use curse of recklessness on him. This will instantly dispel the fear and cause him to ignore any fear effects. He will be really mad at you at this point and come charging straight back at you.
Because an enemy can only have one curse at a time, he will have lost his curse of exhaustion when you used curse of recklessness. As soon as his fear breaks, immediately re apply curse of exhaustion so he loses recklessness. If you don't have exhaustion, you can still use curse of agony or any other curse. If you don't use another curse to replace recklessness, your fears wont affect him. Then just fear him again and keep him running.
You can safely apply other damage over times to the enemy you are fearing while he's running around. I'm pretty good at this and I can kill an enemy this way, and put enough DOTs on other enemies to effectively destroy all the enemies at once. It just takes a lot of concentration.
Practice this technique on mobs a lot before you try it in an instance. After a little practice you can do this safely. Just make sure to warn your group you know what you're doing so they don't boot you when they see fear. People get really mad when you use fear normally. If they're really insistent that you not try this, it may be worth it to not use this technique, even if it would save them. You can recover from a wipe, but not from getting booted from your group.