My observations / tips for completing Forge of Souls as a Hunter...

General
 • This is pretty much the new standard for hunters, but Misdirect followed by volley is so, so great for helping your tank establish initial aggro.
• Some of the pulls are spread out just enough to sometimes be tough for your tank, so be ready with a Freezing Arrow to freeze a caster mob that wasn't picked up.
• If things go badly, the design of Forge of Souls is great for emergency kiting. (Scoff if you wish, but I've had to do this once already.) Long open sight lines and almost no walls to interfere with vision. Pick out a melee mob, Distracting Shot it and get moving! Don't do this to the shadowy spectre things though - they can teleport directly to their targets.

Bronjahm
• Turn on your music. Seriously.
• Stay as far away from Bronjahm as possible. I personally stay right at the entrance ramp, because if he starts to channel/steal my soul, I drop a frost trap and then run down the ramp to get more distance. I drop the trap because...
• The soul fragments can be slowed. This helps a great deal as it gives DPS additional seconds to destroy it before it reaches Bronjahm. If the soul fragment is coming from you, a frost trap should do the trick.  If it's from someone else, toss a Concussive Shot and it should give you plenty of time to destroy it.

Devourer of Souls
• There's not a lot of real strategy to this fight other than to make sure you stop DPS when Mirrored Souls is up. Just watch your party frames for the debuff icon and as soon as it disappears, fire!

Something I just thought of and want to test is if Deterrence will prevent the damage from Mirrored Souls.  This could be a nice, foolproof way of protecting yourself in case the other dps is overeager.