Ok this is the Onxyia Horde chain quest guide.
The Horde attunement quest chain is made up of 14 quests. Due to the difficulty of the quests and the fact that many of them must be completed in 5 man groups it is not advisable to attempt to complete them until level 60. It is possible to do so before, but only with lots of help. The quests are as follows below.
Warlord's Command
Starting + Ending NPC / Location: Warlord Goretooth / Kargath, Badlands
Prerequisite: None
Leads to Quest: Eitrigg's Wisdom
Level Obtained: 55
Quest Level: 63
XP Reward: 8500
Item Rewards: Choose from one of the following:
Wyrmthalak's Shackles Omokk's Girth Restrainer Halycon's Muzzle
Cloth Wrists
37 Armor
+9 Intellect
+15 Spirit
Plate Waist
353 Armor
+15 Strength
+9 Stamina
Equip: Improves your chance to get a critical strike by 1% Leather Shoulder
127 Armor
+22 Intellect
+5 Spirit
+10 Arcane Resistance
Vosh'gajin Strand Voone's Vice Grips
Leather Waist
95 Armor
+9 Strength
+6 Stamina
Equip: Improves your chance to get a critical strike by 1%
Equip: Increases your chance to dodge an attack by 1%
Mail Hands
221 Armor
+6 Strength
+6 Agility
+6 Spirit
Equip: Improves your chance to hit by 2%
Search for more information on this quest: TTH Search Tool
Objectives: Slay Highlord Omokk, War Master Voone, and Overlord Wyrmthalak. Recover Important Blackrock Documents. Return to Warlord Goretooth in Kargath when the mission has been accomplished.
Notes: To get this quest you must listen to all of Warlord Goretooths story before you can access the quest. He will not have a question mark over his head even when you hit a level high enough to access the quest. All of the bosses are located in Lower Blackrock Spire. This must be done as a 5 man group in order for it to count. When you find the documents they will stay there for everyone who needs them in the group to loot.
Eitrigg's Wisdom
Starting NPC / Location: Warlord Goretooth / Kargath, Badlands
Ending NPC / Location: Warlord Goretooth / Ogrimmar
Prerequisite: Warlord's Command
Leads to Quest: For the Horde!
Level Obtained: 55
Quest Level: 63
Search for more information on this quest: TTH Search Tool
Objectives: Speak with Eitrigg in Orgrimmar. When you have discussed matters with Eitrigg, seek council from Thrall.
Notes: You will find Eitrigg in Thralls chamber in Ogrimmar.
For The Horde! (Raid)
Starting + Ending NPC / Location: Thrall / Ogrimmar
Prerequisite: Eitrigg's Wisdom
Leads to Quest: What the Wind Carries
Level Obtained: 55
Quest Level: 63
XP Reward: 10900
Item Rewards: Choose from one of the following:
Mark of Tyranny Eye of the Beast Blackhand's Breadth
Trinket
180 Armor
+10 Arcane Resistance
Equip: Increases your chance to dodge an attack by 1%
Trinket
Classes: Priest, Shaman, Mage, Warlock, Druid
Equip: Improves your chance to get a critical strike with spells by 2% Trinket
Equip: Improves your chance to get a critical strike by 2%
Search for more information on this quest: TTH Search Tool
Objectives: Travel to Blackrock Spire and slay Warchief Rend Blackhand. Take his head and return to Orgrimmar.
Notes: You are allowed to complete this quest in a raid of up to 15 people. Rend is at about the mid point of Upper Black Rock Spire. He is located in the arena area and is part of a scripted event. You must fight your way through several progressively harder waves of dragonkin, orcs and dragon whelps before Rend will appear. When he does he will be riding a mount. You must fight him on his mount for a little while and then he will jump off. It is best to tank him and finish his dragon mount before finishing him off.
What the Wind Carries
Starting + Ending NPC / Location: Thrall / Ogrimmar
Prerequisite: For The Horde!
Leads to Quest:
Level Obtained: 55
Quest Level: 63
XP Reward: 700
Search for more information on this quest: TTH Search Tool
Objectives: Listen to Thrall.
Notes: All you have to do is talk to Thrall and listen to his speech to get the next quest in the chain.
The Champion of the Horde
Starting NPC / Location: Thrall / Ogrimmar
Ending NPC / Location: Rexxar / Desolace
Prerequisite: What the Wind Carries
Leads to Quest: The Testament of Rexxar
Level Obtained: 55
Quest Level: 63
XP Reward: 5500
Search for more information on this quest: TTH Search Tool
Objectives: Seek out Rexxar. The Warchief has instructed you as to his whereabouts. Search the paths of Desolace, between the Stonetalon Mountains and Feralas.
Notes: Rexxar travels the roadways through Desolace, if you stay on the roads and travel around you will eventually find him.
The Testament of Rexxar
Starting NPC / Location: Rexxar / Desolace
Ending NPC / Location: Myranda the Hag / Western Plaguelands
Prerequisite: The Champion of the Horde
Leads to Quest: Oculus Illusions (Raid)
Level Obtained: 55
Quest Level: 63
XP Reward: 5000
Search for more information on this quest: TTH Search Tool
Objectives: Deliver Rexxar's Testament to Myranda the Hag in the Western Plaguelands.
Notes: You can find Myranda just south of Andorhal on the east side in the graveyard. She is sitting on a tree stump.
Oculus Illusions (Raid)
Starting + Ending NPC / Location: Myranda the Hag / Western Plaguelands
Prerequisite: The Testament of Rexxar
Leads to Quest: Emberstrife
Level Obtained: 56
Quest Level: 63
XP Reward: 5000
Search for more information on this quest: TTH Search Tool
Objectives: Travel to Blackrock Spire and collect 20 Black Dragonspawn Eyes. Return to Myranda the Hag when the task is complete.
Notes: To collect the eyes you must raid Upper Blackrock Spire and slay dragonkin. They generally drop in pairs. Once you have received 20, return to Myranda.
Emberstrife
Starting NPC / Location: Myranda the Hag / Western Plaguelands
Ending NPC / Location: Emberstrife / Dustwallow Marsh
Prerequisite: Oculus Illusions
Leads to Quest: The Test of Skulls, Scryer; The Test of Skulls, Somnus; The Test of Skulls, Chronalis
Level Obtained: 56
Quest Level: 63
XP Reward: 5400
Search for more information on this quest: TTH Search Tool
Objectives: Travel to the Wyrmbog in Dustwallow Marsh and seek out Emberstrife's Den. Once inside, wear the Amulet of Draconic Subversion and speak with Emberstrife.
Notes: Emberstrife's cafe is located in the south of Dustwallow Marsh. Once you reach there you should put on the amulet of Draconic Subversion that Myranda gave you. Once on you will transform into a Black Scalebane Dragonkin. At this point you can talk to Emberstrife just as you would any other NPC. Emberstrife will now give you 3 quests, you can take them one at a time or all three at once. I would suggest getting all three, finish them and then return for the fourth and final quest he gives you.
The Test of Skulls, Scryer
Starting + Ending NPC / Location: Emberstrife / Dustwallow Marsh
Prerequisite: Emberstrife
Leads to Quest: The Test of Skulls, Axtroz
Level Obtained: 56
Quest Level: 63
XP Reward: 7200
Search for more information on this quest: TTH Search Tool
Objectives: You must find the blue dragonflight drake champion, Scryer, and slay him. Pry his skull from his corpse and return it to Emberstrife. You know that Scryer can be found in Winterspring.
Notes: Scryer can be found in Winterspring. Follow the road south of Everlook and then west into the dragonkin area. He is near the end of the dragon cave system and is a level 60 elite.
The Test of Skulls, Somnus
Starting + Ending NPC / Location: Emberstrife / Dustwallow Marsh
Prerequisite: Emberstrife
Leads to Quest: The Test of Skulls, Axtroz
Level Obtained: 56
Quest Level: 63
XP Reward: 7200
Search for more information on this quest: TTH Search Tool
Objectives: Destroy the drake champion of the Green Flight, Somnus. Take his skull and return it to Emberstrife.
Notes: Somnus can be found in the Swamp of Sorrows. He is a level 62 elite and can be found along the south east coast of the zone.
The Test of Skulls, Chronalis
Starting + Ending NPC / Location: Emberstrife / Dustwallow Marsh
Prerequisite: Emberstrife
Leads to Quest: The Test of Skulls, Axtroz
Level Obtained: 56
Quest Level: 63
XP Reward: 7200
Search for more information on this quest: TTH Search Tool
Objectives: Guarding the Caverns of Time in the Tanaris Desert is Chronalis, child of Nozdormu. Destroy him and return his skull to Emberstrife.
Notes: Chronalis can be found along the east edge of the Tanaris desert at the gates to the Caverns of Time. He is a level 61 elite and is immune to shadow and arcane spells.
The Test of Skulls, Axtroz
Starting + Ending NPC / Location: Emberstrife / Dustwallow Marsh
Prerequisite: The Test of Skulls, Scryer; The Test of Skulls, Somnus; The Test of Skulls, Chronalis
Leads to Quest: Ascension...
Level Obtained: 56
Quest Level: 63
XP Reward: 7200
Search for more information on this quest: TTH Search Tool
Objectives: Travel to Grim Batol and track down Axtroz, drake champion of the Red Flight. Destroy him and take his skull. Return the skull to Emberstrife.
Notes: Axtroz is a level 61 Elite and can be found in the north-east of the Wetlands. He is considered by many the easiest of the 4 dragons in the test of skulls chain.
Ascension...
Starting NPC / Location: Emberstrife / Dustwallow Marsh
Ending NPC / Location: Rexxar / Desolace
Prerequisite: The Test of Skulls, Axtroz
Leads to Quest: Blood of the Black Dragon Champion (Raid)
Level Obtained: 56
Quest Level: 63
XP Reward: 5400
Search for more information on this quest: TTH Search Tool
Objectives: It would appear as if the charade is over. You know that the Amulet of Draconic Subversion that Myranda the Hag created for you will not function inside Blackrock Spire. Perhaps you should find Rexxar and explain your predicament. Show him the Dull Drakefire Amulet. Hopefully he will know what to do next.
Notes: You must once again travel to Desolace and talk to him, this time it will lead to the final quest in the Horde Onyxia attunement chain.
Blood of the Black Dragon Champion (Raid)
Starting + Ending NPC / Location: Rexxar / Desolace
Prerequisite: Ascension
Leads to Quest: N/A
Level Obtained: 56
Quest Level: 63
XP Reward: 10500
Item Reward:
Drakefire Amulet
Unique
Neck
+10 Stamina
+15 Fire Resistance
Search for more information on this quest: TTH Search Tool
Objectives: Travel to Blackrock Spire and slay General Drakkisath. Gather his blood and return it to Rexxar.
Notes: You are allowed to raid this quest with up to 15 players. General Drakkisath is the final boss in Upper Blackrock Spire. Once you have killed him he will drop 2 to 4 blood. You may have to run UBRS several times to get yours if many people in your group need the blood.
Conclusion
At this point you have finished the Horde Onyxia attunement chain and can proceed onto raiding Onyxia's lair.