Harp, Minstrel. I'm in.
I don't think the strategy thread you posted is the most reliable way to down Thorog. So, for what it's worth, here's the strategy that's worked for me. Feel free to ignore if you really want to try it the other way.
In my experience: the fewer folks you have who are on or near the main platform and can get the Eye, the less likely it is your raid will wipe to the Eye. High Fear resist chance does help prevent the Eye so it pays to have folks with high Fear resist in the main platform group. If you can avoid wiping to the Eye, it's basically just a really long tank-n-spank... with the "spank" coming mostly from hunter DPS.
IMO this fight is actually simpler than Thaurlach with this strategy... except that you need 18 people really on their game vs 9 with the Balrog. This is a 9 dread fight, so chain hope is very helpful.
Here's a map I drew that shows the positions of the four groups:
I really like pulling Drugoth up to the perch. His long, slow walk back to his crypt gives everyone plenty of time to pop hope and eat. The MT group can jump down from the perch and walk (or hobble) to the main platform with plenty of time to spare.
MT Support group: Guardian, Captain, Captain, Minstrel, Minstrel, Loremaster
All of Thorog's non-Eye attacks on the MT group can be healed through. One captain keeps Muster Courage up continuously for the +20% fear resist and the other hits his when someone gets the Eye. Almost always, a fear pot + Muster Courage clears the Eye, but the player with the eye should run for quarantine while eating the pot and waiting for Muster Courage, just to be sure. Getting out of LoS of Thorog always clears the eye within 3 seconds.
Adds group: Champ, Grd, Mns, LM, (flexible x2)
One or two champs from this group can be a floaters down on the platform DPSing/clobbering Thorog. The MT group minstrels can keep the champs healed, but they will need to manage their own fear effects with pots/runs to the quarantine spot. The Adds group guardian's job is to scoop up every add that tries to get to the hunters. LM can mez/root spiders as needed, and Wind-lore + Raven-ranged-debuff the drakes to coax them to come up to the perch. LMs feed power to the hunters as they can. The burglars from the Interrupt group provide the DPS to down the adds.
Ranged DPS group: Hunter x5, (flexible x1)
Two hunters with good graphics cards and max draw distance are responsible for tagging the adds before they head to the MT group (they don't DPS the adds, just tag them so they try to come up to the hunters perch). All hunters DPS Thorog as much as possible while he's on the platform. When he flies up to heal, hunters can assist clearing the adds. It's rare, but Hunters (or anyone else on the very edge of the perch) can get the Eye - just run up to the healing platform or drop behind the E stairs to break LoS.
Interrupt group: Burglar x3, Hunter x2, (flexible x1)
Burglars
must land a named conjunction on Thorog to prevent him from healing to full. "All yellows!" does the trick. Burglars must plan primary and secondary FM starters for each time Thorog flies up. All other burgs debuff Thorog on incoming to improve the chances of the FM landing. When Thorog is down on the main platform, burglars watch for the Eye on the MT group and assist in killing adds.
The hunters in this group act as if they are part of the Ranged DPS group - see above.