Mikrul is first, and more deadly than ever- he retains the life-leeching effect that used to spring from his weapon, and this time his draugr thralls are armed and armored, and thus able to hack you apart. Some even use Apprentice and Adept level magic to bombard you (and their own allies) from a distance. A distracting follower is a must here unless you happen to have a powerful enough (and powerfully enchanted enough) weapon to try and handle the ghostly traitor in a few swift strikes- anything taking more than about five seconds will result in your back getting hacked open by the miscellaneous draugr. If you're attacking him from a distance, it pays to leap from ledge to ledge over the spaces the coffins in the walls create- Mikrul and his thralls don't know how to leap and thus have to use the stairs, buying you precious moments to plant spells and arrows in their heads.
Sigdis comes forwards second, to reprise his cups-and-balls archer game. To make things more difficult this time, his false images also have horns on their helmets- the trick is that the images' horns point straight up where Sigdis' are curled. He is a bit tougher than last time, but not by enough to mean much- if you can handle discerning which is an image and which is actually Sigdis, you'll be just fine.
Jyrik is last, and he's a bit of a doozy. Rather than his previous game of being an indestructible melee caster, he teleports around the room every so often, pelting you with ice to prevent you from having the stamina to catch up with him. Thankfully, Magicka is a limited resource, so a hefty helping of Magicka poison will render this a much, much easier battle. Again, a distracting follower is vital here, as they don't use poison, and you can apply it to attacks against the diverted spectre.
Once all three Gauldurson brothers are slain again (again), they will rise and ready to attack you simultaneously from the altar. They are stopped, though, when a voice shouts from behind them- and then an explosion of brilliant light banishes the three from the land of Skyrim for all eternity. The glow subsides for a short time, then pulses again- and becomes a column over the altar, in which the Gauldur Amulet hangs suspended, waiting for you to recieve it.
While the necklace lacks the incredible powers credited to it by legend, it does still improve all three of your resource pools (Magicka, Health, and Stamina) by 30 points each, which is definitely nothing to sneeze at. You can also advance over the altar to the ledge behind it, where the open coffin reveals the skeleton of Gauldur himself, which holds a decent amount of coin for you to take.
If you head straight out of the room to the far wall of the intersection you probed before, though, you can recieve a much more worthy reward- some valuable gear, a coin purse, and a chest that frequently contains one of the rare Daedric cheeses.
With the amulet reunited and three of the most fearsome villains ever to grace Skyrim permanently dealt with, you are now done with the Forbidden Legend.