The (Advanced Solo) can be done with either a Mercenary or as a duo with another player. You must be level 92 to enter the zone and have the Chains of Eternity expansion. The Ashlok sometimes whip you towards and behind them, so take care what you're facing to prevent falling down.
Names spawn as the preceding one is killed.
Despite appearances the zone is actually quite linear: once you find the ramp up to the platforms there's really only one way to go, with each named a bit further along the route.
Level 95^ spider. Burn down fast. He will drop white sacks that hatch into several spiders. These sacks have a lot of hitpoints, so better focus on killing the boss. ( -38, 2, -116 ) Copy/waypoint -38, 1.6, -116
Dirge strat: Aracanocht itself is fairly easy but it prevents you from changing targets at some point, so you have to kill the adds. With a Dirge, use Veil of Notes (Heroic AA, 20 seconds of 100% Dodge) when the tiny bonedevourers spawn, then focus on green abilities (area effect). They don't have a lot of life. Once they die Aracanocht should become the main target again, and Veil of Notes will run out. At this point you should be able to kill it before new adds spawn. Use Howl of Death and Thuri's to heal yourself throughout.
Kill the adds first, they fear and if not cured will possibly break the encounter by you falling from the platform. They are also weaker if you take them out first and fear noticeably less.
Errlik will occasionally fling you straight up in the air. ( 10, 67, -51 ) Copy/waypoint 10, 67, -51
Joust when he yells "Claws! SLASH!" (at 80%, 60%, 40% and 20% health). He will root himself and deal massive AOE damage. Make sure your merc isn't near him when this happens. ( 12, 67, -47 ) Copy/waypoint 12, 67, -47
He has a 15% chance every 15 seconds hit you with "Necrotic Bone Shards" - which is cureable within 3 seconds, or can daze you and deal damage to health and energy.
He can also spawn whirlwinds and toss you into the air. ( -1, 108, -201 ) Copy/waypoint -0.9, 108, -201