We no longer struggle with this, though it got us stuck for a while. (This is for 10 man... we only have enough for that.)
One tank (me, for this fight) charges in and agros ALL mobs, holding them on the top of the platform. After a few seconds the other tank comes in and taunts Faerlina to the side, on the steps. Those few seconds are critical. The adds are oddly keen to run off after Faerlina, no idea why.
We have a mage and a healer on the platform. I gather the mobs (shield bash and heroic throw are perfect for this, so don't use it on the pull) in a neat group and mage AoEs, down to about 20%, depending on how fine you can do it. Some people take them as low as 5%, but I prefer a nice margin. Tab target to keep all of them even and on you. Interrupt where possible to save your healer a bit, but they really do NOT hit hard. At this point you're just iddling. There's no skill required.
Once you get them down to your predefined health, stop aoe and mage goes onto boss. When she is about to frenzy mage goes onto your target (meaning it's up the OT to be targetting the right add) and kills it very dead. Rinse and repeat.
Ignore the rain of fire. It doesn't do much damage and you're better off keeping everything in the right position than trying to chase things around. Faerlina can be moved if you want, to spare the melee DPS, but it's not necessary.
Once the last add is dead, both healers go onto targetting the MT, and the other tank goes to DPS on Faerlina as well.
Try to kill her before she kills the tanks.
There are a couple of things that can go wrong.
1. Make sure NO DPS other than the single assigned mage (or whatever) hit an add, for any reason whatsoever. We've had death knights (it's always DKs, for some reason) decide to helpfully slaughter the adds.
2. Make sure you're not too close. If you have one add getting hit by AoE on Faerlina you'll struggle to get them down evenly.
3. Make sure you're not too far away. The area of effect for the Embrace isn't all that big. Err on the side of caution and pull one over before you kill it if need be.
This makes for very easy raid instructions for all but the the one DPS: "Kill the skull."