From Ultimate Combat:
"Benefit: When you are adjacent to an ally with this feat, the first time you melee attack an opponent, you can spend an immediate action to take a 5-foot step, even if you have otherwise moved this round.
Normal: You can take a 5-foot step only if you have not otherwise moved in a round."
So I can't tell if this feat is simply incredibly poorly written, or whether I am missing some critical portion of the rules which makes it clear.
The way I had read and played this feat is that if I was adjacent to an ally who also had this feat when I first attacked an opponent during a round, I was able to use an Immediate action to take a five foot step, in addition to my normal movement if any for that round. I also recognize that as an immediate action, I could take that five foot step out of my own round, for instance if I make an attack of opportunity.
Mostly though I was using this to make multiple five foot steps within a round (two) so that I could get into flanking positions against enemies, which fits the feat's flavor text "You are skilled at surrounding your enemies."
Now, my friend who is a GM read this description and is convinced that this only applies once per encounter, because it doesn't say "the first time each round" or else that it only applies the first time you attack a specific enemy, because it says "the first time you attack AN ENEMY."
I don't think either of those readings are reasonable, but he's the GM and I'm not going to argue with him about it. I just swapped out the feat for another.
But this feat is very flavorful and handy, and fits with my character very well. I would like to be able to use it, but sadly am unable given its ambiguous wording. Help.