If you are confused like me as to how to start the ritual, once you are on the platform, cast Ritual of Doom. It is in the general tab of your spellbook. That will summon an interact-able item that you and the other two warlocks will need to click to get the demon to appear.
You need to research Grand Crusade in your Order hall to get these.
This item allows you to instant complete one (non-elite, non-invasion) world quest. You can make the item in your order hall once a day for x100 Order Resources and ten minutes time. You can use this item once every 18 hours (this is likely to prevent you from stockpiling the items).
After you pick up this quest, you need to talk to Terric the Illuminator again to actually "send out the call." This costs 100 resources and takes ten minutes of time and will reward to you with the item you need to insta-complete a (non-elite, non-invasion) world quest.
If Terric the Illuminator does NOT have a dialogue option to order the the Silver Hand Orders and complete the quest, (this has happened to me on two paladins now), just log in and out to fix.
This is one half of the two items needed for the hidden appearance for Outlaw rogues. It is the appearance of the classic Thunderfury, Blessed Blade of the Windseeker except, you know, one for each hand.
To get this, you need this half as well as the Bindings of the Windlord from the last boss in Neltharion's Lair. These items can drop on any difficulty, including normal. The drop rate was raised in patch 7.2 so it shouldn't require too many runs to get them now.
Once you get both bindings, obtain x10 Infernal Brimstone (you will need this for the final stage of the quest) and then head to Vethir in Stormheim. For Alliance, you can find him at Lorna's Watch and for Horde, he will be at Cullen's Post. Do note that you need to have done enough of the Stormheim quest chain to have "unlocked" his presence. Talk to Vethir and he will give you several dialogue options. Select the one that sends you to the top of Thorim's Peak.
Once up there, you need to speak to Thrymjaris. You must be in Outlaw spec for her to offer the correct dialogue options. The second choice will reference a Windlord. That's the one you want.
Select it and and Thunderaan should appear and have a bit of dialogue and then offer Audience with the Windlord. Complete that and receive your hidden appearance!
This is one half of the two items needed for the hidden appearance for Outlaw rogues. It is the appearance of the classic Thunderfury, Blessed Blade of the Windseeker except, you know, one for each hand.
To get this, you need this piece from the last boss in Neltharion's Lair and Bindings of the Windlord from the Golem boss in Vault of the Wardens. These items can drop on any difficulty, including normal. The drop rate was raised in patch 7.2 so it shouldn't require too many runs to get them now.
Once you get both bindings, obtain x10 Infernal Brimstone (you will need this for the final stage of the quest) and then head to Vethir in Stormheim. For Alliance, you can find him at Lorna's Watch and for Horde, he will be at Cullen's Post. Do note that you need to have done enough of the Stormheim quest chain to have "unlocked" his presence. Talk to Vethir and he will give you several dialogue options. Select the one that sends you to the top of Thorim's Peak.
Once up there, you need to speak to Thrymjaris. You must be in Outlaw spec for her to offer the correct dialogue options. The second choice will reference a Windlord. That's the one you want.
Select it and and Thunderaan should appear and have a bit of dialogue and then offer Audience with the Windlord. Complete that and receive your hidden appearance!
Once you get both bindings, obtain x10 Infernal Brimstone (you will need this for the final stage of the quest) and then head to Vethir in Stormheim. For Alliance, you can find him at Lorna's Watch and for Horde, he will be at Cullen's Post. Do note that you need to have done enough of the Stormheim quest chain to have "unlocked" his presence. Talk to Vethir and he will give you several dialogue options. Select the one that sends you to the top of Thorim's Peak.
Once up there, you need to speak to Thrymjaris. You must be in Outlaw spec for her to offer the correct dialogue options. The second choice will reference a Windlord. That's the one you want.
Select it and and Thunderaan should appear and have a bit of dialogue and then offer Audience with the Windlord. Complete that and receive your hidden appearance!
No where in-game does it make it clear what the objective of the puzzle is, so don't feel bad if you don't know what to do immediately. Talk to the owl statue to start the sequence in the room where you just killed the boss. Several owl statues will appear in the room. Clicking one statue will hide it but expose its neighbours. The goal is to have only the middle pillar standing. Once only the middle one remains, clicking it will complete the sequence for quest credit.
If you don't feel like figuring out the puzzle on your own, here is the pattern to hit, with statue spaces listed in order:
Basically select one corner and then run down the side clicking each one as you go. From there is should be clear to hit to hit the 6th and 7th position to clear that side. Then you go to the opposite end of the room for the 8th statue, which will leave just the middle statue (marked with the yellow box) up. Click that one to finish the sequence, and you can now head off to kill Cordana.
As a note, if you mess up, you can talk to the sparkly owl statue at the start of the room again to reset the puzzle. If you weren't the person in your party to start the puzzle, they will need to talk to the statue.
Unlike every other profession thing in the game now, you can't complete this with the materials in your bank. You'll need your x 12 Purified Fiendish Leather and x 12 Lightweave Cloth in your inventory ( Enstraa's Tanning Oil is given to you by the NPC when you pick up the quest) in order to make the items needed for completion.
You will need at least skill level 485 in Tailoring to complete this quest, as it requires recipes all the way up to Cataclysm-era. All of these recipes can be obtained from the Tailoring trainers directly; there are no vendor or drop recipes necessary.
You must craft all of these items in front of the quest giver to get credit (although you can bolt the cloth elsewhere). Obviously, this means you cannot buy the robes premade or anything like that.
0
If you are confused like me as to how to start the ritual, once you are on the platform, cast
Ritual of Doom. It is in the general tab of your spellbook. That will summon an interact-able item that you and the other two warlocks will need to click to get the demon to appear.
0
He's in the Falanaar Ruins, not on the surface. Use the back tunnel entrance to get to him.
0
If you see him in your class hall and have completed the stones in the portals, go into feral spec and /sit to get your feral hidden appearance.
0
This class hall quest involves doing the main storyline from Val'sharah to complete. It starts with https://www.wowdb.com/quests/38305-cenarius-keeper-of-the-grove in Lorlathil.
0
This class hall quest involves doing the main storyline from Val'sharah to complete. It starts with https://www.wowdb.com/quests/38305-cenarius-keeper-of-the-grove in Lorlathil.
0
(This item is not dropped by Elegon)
2
You need to research
Grand Crusade in your Order hall to get these.
This item allows you to instant complete one (non-elite, non-invasion) world quest. You can make the item in your order hall once a day for x100
Order Resources and ten minutes time. You can use this item once every 18 hours (this is likely to prevent you from stockpiling the items).
0
After you pick up this quest, you need to talk to Terric the Illuminator again to actually "send out the call." This costs 100 resources and takes ten minutes of time and will reward to you with the item you need to insta-complete a (non-elite, non-invasion) world quest.
If Terric the Illuminator does NOT have a dialogue option to order the the
Silver Hand Orders and complete the quest, (this has happened to me on two paladins now), just log in and out to fix.
0
This is one half of the two items needed for the hidden appearance for Outlaw rogues. It is the appearance of the classic
Thunderfury, Blessed Blade of the Windseeker except, you know, one for each hand.
To get this, you need this half as well as the
Bindings of the Windlord from the last boss in 
Neltharion's Lair. These items can drop on any difficulty, including normal. The drop rate was raised in patch 7.2 so it shouldn't require too many runs to get them now.
Once you get both bindings, obtain x10
Infernal Brimstone (you will need this for the final stage of the quest) and then head to Vethir in Stormheim. For Alliance, you can find him at Lorna's Watch and for Horde, he will be at Cullen's Post. Do note that you need to have done enough of the Stormheim quest chain to have "unlocked" his presence. Talk to Vethir and he will give you several dialogue options. Select the one that sends you to the top of Thorim's Peak.
Once up there, you need to speak to Thrymjaris. You must be in Outlaw spec for her to offer the correct dialogue options. The second choice will reference a Windlord. That's the one you want.
Select it and and Thunderaan should appear and have a bit of dialogue and then offer Audience with the Windlord. Complete that and receive your hidden appearance!
0
This is one half of the two items needed for the hidden appearance for Outlaw rogues. It is the appearance of the classic
Thunderfury, Blessed Blade of the Windseeker except, you know, one for each hand.
To get this, you need this piece from the last boss in
Neltharion's Lair and 
Bindings of the Windlord from the Golem boss in 
Vault of the Wardens. These items can drop on any difficulty, including normal. The drop rate was raised in patch 7.2 so it shouldn't require too many runs to get them now.
Once you get both bindings, obtain x10
Infernal Brimstone (you will need this for the final stage of the quest) and then head to Vethir in Stormheim. For Alliance, you can find him at Lorna's Watch and for Horde, he will be at Cullen's Post. Do note that you need to have done enough of the Stormheim quest chain to have "unlocked" his presence. Talk to Vethir and he will give you several dialogue options. Select the one that sends you to the top of Thorim's Peak.
Once up there, you need to speak to Thrymjaris. You must be in Outlaw spec for her to offer the correct dialogue options. The second choice will reference a Windlord. That's the one you want.
Select it and and Thunderaan should appear and have a bit of dialogue and then offer Audience with the Windlord. Complete that and receive your hidden appearance!
0
This is the hidden appearance for Outlaw rogues. It is the appearance of the classic
Thunderfury, Blessed Blade of the Windseeker except, you know, one for each hand.
To get this, you need
Bindings of the Windlord from the last boss in 
Neltharion's Lair and 
Bindings of the Windlord from the Golem boss in 
Vault of the Wardens. These items can drop on any difficulty, including normal. The drop rate was raised in patch 7.2 so it shouldn't require too many runs to get them now.
Once you get both bindings, obtain x10
Infernal Brimstone (you will need this for the final stage of the quest) and then head to Vethir in Stormheim. For Alliance, you can find him at Lorna's Watch and for Horde, he will be at Cullen's Post. Do note that you need to have done enough of the Stormheim quest chain to have "unlocked" his presence. Talk to Vethir and he will give you several dialogue options. Select the one that sends you to the top of Thorim's Peak.
Once up there, you need to speak to Thrymjaris. You must be in Outlaw spec for her to offer the correct dialogue options. The second choice will reference a Windlord. That's the one you want.
Select it and and Thunderaan should appear and have a bit of dialogue and then offer Audience with the Windlord. Complete that and receive your hidden appearance!
0
This is done in the Beholder boss' room (once he is dead) in
Vault of the Wardens.
No where in-game does it make it clear what the objective of the puzzle is, so don't feel bad if you don't know what to do immediately. Talk to the owl statue to start the sequence in the room where you just killed the boss. Several owl statues will appear in the room. Clicking one statue will hide it but expose its neighbours. The goal is to have only the middle pillar standing. Once only the middle one remains, clicking it will complete the sequence for quest credit.
If you don't feel like figuring out the puzzle on your own, here is the pattern to hit, with statue spaces listed in order:
Basically select one corner and then run down the side clicking each one as you go. From there is should be clear to hit to hit the 6th and 7th position to clear that side. Then you go to the opposite end of the room for the 8th statue, which will leave just the middle statue (marked with the yellow box) up. Click that one to finish the sequence, and you can now head off to kill Cordana.
As a note, if you mess up, you can talk to the sparkly owl statue at the start of the room again to reset the puzzle. If you weren't the person in your party to start the puzzle, they will need to talk to the statue.
0
Unlike every other profession thing in the game now, you can't complete this with the materials in your bank. You'll need your x 12
Purified Fiendish Leather and x 12 
Lightweave Cloth in your inventory (
Enstraa's Tanning Oil is given to you by the NPC when you pick up the quest) in order to make the items needed for completion.
0
You can do this on heroic or mythic, but not mythic+.
0
You will need at least skill level 485 in Tailoring to complete this quest, as it requires recipes all the way up to Cataclysm-era. All of these recipes can be obtained from the Tailoring trainers directly; there are no vendor or drop recipes necessary.
You must craft all of these items in front of the quest giver to get credit (although you can bolt the cloth elsewhere). Obviously, this means you cannot buy the robes premade or anything like that.
The total materials needed to craft everything: