Here is a link (and quoted info from the page) about the Teir .5 sets. It has links to the actual sets as well.
Step One: Bracers
Bracers are the first piece to be upgraded.
Horde Crest Horde
The questgiver for the Horde is found in Thrall's Chamber. He tells you to collect 15 Venom Samples from Spiders/Scorpions in Silithus, and bring these and 20gold to him. He's one of the guys across the room from Thrall. The drop rate isn't bad, it only takes about a half hour.
Alliance Crest Alliance
For the Alliance, the quest giver is the human NPC named Deliana just inside the Ironforge throne room. She requires 15 Blood Samples from the bears and/or wintersabers in Winterspring, as well as 20gold. The drop rate seemed to be 30-50%, so it's not bad at all. If you intend to do the next step of the chain to get the gloves and belt, you can save a return trip (as well as 10gold) by picking up a Fel Elemental Rod before you leave. See the Winterspring section below for more info.
After giving you your shiny new bracers, they send you to Gadgetzan to talk to a friend of theirs.
Step Two: Belt and Gloves
In Gadgetzan, you talk to one Mux Manascrambler. He requests 1 Delicate Arcanite Converter, 4 Greater Eternal Essence, 10 Stonescale Oil, and 40gold, as well as 25 "Volcanic Ash", obtained from Lava Pools in Burning Steppes. He wants this to build an "Ectoplasmic Distiller" for his newest project, an "extra-dimensional ghost revealer". Volcanic Ash can be found all over the place, and looks just like the dirt piles found in Un'Goro Crater. You get 1-3 Volcanic Ash per pile, and it is a Quest Item (soulbound, only lootable if on the quest). Collecting these won't take long, maybe 15 minutes.
After assembling the Ectoplasmic Distiller, Mux sends you off with it to gather Ectoplasms; twelve each from Silithus, Winterspring, and Eastern Plaguelands. The Ectoplasmic Distiller is an item that you Use (right click) to drop in the game world, like a Shaman's totem. Doing so consumes 1 Goblin Rocket Fuel. The Distiller will remain on the ground for around 5 minutes. When you are nearby, you recieve a buff that allows you to collect Ectoplasm from the corpses of dead ghosts. You must have the buff at the time the mob dies in order to be able to loot the Ectoplasm.
The tortured night elves in Silithus are located in Southwind Village, along the middle of the eastern mountains. When you kill them, they spawn 0-3 bugs, which really limits how quickly you can kill them. (Warlocks can use Howl of Terror when the mob is nearly dead.)
The best place for Stable Ectoplasm in Eastern Plaguelands is Northdale, as there are nothing but ghosts there (but watch out for fear). Both the Banshees as well as the invisible ghosts will drop Ectoplasm. Have a Warlock buff you with Detect Greater Invisibility before heading here to avoid unwanted multi-pulls.
Head to Lake Kel'Theril. Any of the mobs on the lake will drop it, but there are some ruins on the northwest part of the lake with very high concentrations of them. Southwest of the lake there are some more ruins with many ghosts. Tip: While in Winterspring, you can also pick up the "Fel Elemental Rod" that you'll need in a couple steps. This will save you a trip. See below for more info.
* To maximize your fuel, wait to drop the Distiller until just before your first enemy dies.
* The distiller will vanish if you get too far away from it (it's forgiving, about 50-60 yards).
* Multiple players (of the same faction) can share a single Distiller by pulling mobs to it. However, only one Ectoplasm can be looted per mob, so being in a group won't help. Also, you will not get the buff from a Distiller that somebody of the opposite faction dropped.
* With careful planning and fast kills, it is possible to complete this quest with the eight Goblin Rocket Fuel that Mux gave you. However, classes that kill slowly will likely need more, so plan ahead and bring extras.
Burning Steppes: Magma Lord Bokk
Once you've taken these back to him, he tells you to go back to Burning Steppes and kill Magma Lord Bokk and bring back his Magma Core. Bokk is non-elite, and quite easily soloable. You can find him hanging out at the northern tip of the lava pool (it shows up on the map) that's just west of the Pillar of Ash, loc around 35,58. He looks like a big Earth Elemental.
Winterspring: Fel Elemental Rod
Next, Mux will send you to Winterspring to get a "Fel Elemental Rod". It is purchased from the imp Vi'el (map), who resides in a cave near the entrance to Darkwhisper Gorge. You can sneak past the two Hederine Slayers at the entrance to the gorge, and also past the Felhound at the mouth of the cave if you pay careful attention to its patrol route. Purchase the rod from Vi'el for 50gold and take it back to Mux.
If you buy the rod earlier on in the quest line (before the "Fel Elemental Rod" becomes a needed quest item), Vi'el will sell it to you for 40gold, as Mux suggests he should.
After giving Mux the Fel Elemental Rod, he will send you back to your original questgiver (in Ironforge/Orgrimmar), who asks for the dungeon 1 set belt and gloves in exchange for the Dungeon 2 belt and epic gloves.
Step Three: Pants, Shoulders, and Boots
Your next step takes you, along with the Extra-Dimensional Ghost Revealer, to the entrance of Stratholme to talk with the ghost of Anthion Harman. He asks you to rescue Ysida Harmon from Baron Rivendare. The quest is a timed event, requiring the group to engage Baron Rivendare in combat within 45 minutes once the second gate from the Stratholme service entrance has been opened.
* NOTE: The rumour about using Spectral Essence to talk to the prisoner at the end is not true. Did strath in 1h on 3/30, and equipping at the end didn't reveal anyone.
* WARNING: Using the Medallion of Faith and summoning Aurius for the Baron Rivendare fight seems to break the quest script and hence making this quest impossible to complete.
After the 45 min baron run you return to the ghost and he asks you for 3 Dark Iron Bar, 3 Mooncloth, 20 Enchanted Leather, and 4 Cured Rugged Hide. After you turn these in, he sends you to Dire Maul library to talk to Falrin Treeshaper.
Falrin Treeshaper in Dire Maul gives you a quest to gather 25 Ogre Warbeads off the ogres in Dire Maul and Lower Blackrock Spire. The droprate goes (roughly) as follows: Dire Maul (Outside): 1:30, Dire Maul (North): 1:5, Lower Blackrock Spire: 1:2.
Although the drop rate is much higher in Lower Blackrock Spire, there is also much fewer ogres in that instance. It will require multiple runs of either instance to obtain all of the Ogre Warbeads required.
Jeering Spectre's Essence
Once you have 25 Ogre Warbeads, you return to Falrin Treeshaper. He will send you to gather 4 Dark Rune, 8 Large Brilliant Shard, and 1 Jeering Spectre's Essence (which will drop off ghosts in DM West.) The essence is a group drop and you do not need the quest to recieve it. Afterwards, return to the librarian he gives you a banner to take to BRD. Immediately after recieving the banner, you will be attacked by 5 to 6 ghosts which will spawn close by. It does not seem to matter if you win the battle or not.
Top Piece of Lord Valthalak's Amulet
Once you get the banner, you have to go to BRD and kill Theldren's Army and retrieve the Top Piece of Lord Valthalak's Amulet. To do this, just go in the arena, use the banner while the dwarf is "sentencing" you, and destroy all the mobs that come out of the gates. NOTE: Do not forget to get the Top Piece of Lord Valthalak's Amulet from Theldren.
These mobs behave like a pvp group with a mage, healer, warrior, rogue, and sometimes a dynamite tossing goblin. Can't taunt them so they go for healers. Not too hard if done with a mage.
The completion of the event spawns a box of loot and you get to keep the banner in case you want to get the loot again in the future.
You turn in the quest to the NPC at the Stratholme enterance at which point he will send you back to IF/Org.
At this point, you receive your Dungeon 2 Pants, Shoulders, and Boots. (Pants and Shoulders are blue, Boots are epic.)
Step Four: Helm and Chest
Go to Blackrock Mountain and talk to a ghost right outside the BRS entrance using your ghost revealer. He gives you the quest "Three Kings of Flame" which requires you to collect 1 Incindicite of Incendius, 1 Ember of the Emberseer, 1 Cinder of Cynders, and 1 Hallowed Brazier. To get these, you have to kill Incendius in BRD, Emberseer in UBRS, The Duke of Cynders in Silithus, and obtain honored with the Argent Dawn to buy a Hallowed Brazier (120gold) from an Argent Dawn Quartermaster. The Duke of Cynders will be the hardest, since you must collect all the twilight gear to summon a duke, and have only a one in four chance of getting the Duke of Cynders. Note that if you turn in Twilight texts to the hermit Ordell, he may send you a scroll in the mail that will allow you to summon the correct duke. The item you want is Scroll: Create Signet of Beckoning.
The Left Piece of The Amulet
You need to complete one of the following quests
You receive one of the following quests at random. People of the same and different classes have received different quests. You will need to complete that quest before moving on to your "summon" quest, which is the step after this.
Each of these quests requires you to get 1 item from somewhere in the game world, and return it the ghost in BRM. The drop rate on each quest seems to be about equal, anywhere from 5-20 kills. Easily doable by 2 people.
* Go to Purgation Isle in Hillsbrad Foothills and kill Condemned Monks, Cursed Paladins or Writhing Mages for the Soul Ashes of the Banished. When you turn in this quest, you are sent to Scholomance to summon the spirit of Kormok in Ras Frostwhisper's chamber.
* Go to Tyr's Hand in Eastern Plaugelands and kill Preatorians for the Brilliant Sword of Zealotry. They are found toward the rear of Tyr's Hand. When you turn in this quest, you are sent to Scarlet Stratholme to summon the spirits of Jerien and Sothos in Grand Crusader Dathrohan's chamber.
* Go to Hive'Regal in Silithus and kill Hive'Regal Burrowers, Hive'Regal Spitfires or Hive'Regal Slavemakers for the Druidical Remains. When you turn in this quest, you are sent to Lower Blackrock Spire to summon the spirit of Mor Grayhoof in Warmaster Voone's chamber.
* Go to Frostwhisper Gorge in Winterspring and kill Frostmaul Giants or Frostmaul Preservers for the Starbreeze Village Relic. When you turn in this quest, you are sent to Dire Maul East to summon the spirit of Isalien in Alzzin the Wildshaper's chamber.
Note, that as long as you've done the first half of the summoning quest; gathering the reagents and turned them in for the next step, you do not have to do YOUR summon quest. If your quest says to perform the summoning in Balnazzar's room, but you have a guildmate who needs to summon Mor Grayhoof in Lower Blackrock Spire, you can help kill her, and loot your left (or right) piece of the amulet. You then turn in the amulet and move onto the next step of the quest. It is unknown if bosses summoned with the *final* brazier you receive at the end of the quest line will drop the amulet pieces for people on that step of the quest.
The ghost outside of BRS will send you to gather 20 Bloodkelp from Alcaz Island in Dustwallow Marsh. Bloodkelp can drop in quantities of 1-2 from the 59-60 Elite Nagas or in quantities of 1-3 from "Bloodkelp Baskets", usually found near or inside the various buildings on the island.
The Right Piece of The Amulet
Now you need to do another of the quests listed at The Left Piece of The Amulet. The quests are once again random and you may receive the right piece the same way you received your left piece.
Upper Blackrock Spire
Return to the Ghost outside of BRS with the quest item and he will send you to gather Bracers off of Orcs in BRS. Accounts state that the Orcs in UBRS have a much higher drop rate than the Orcs in LBRS. Your mileage may vary.
Once again return to the Ghost outside of BRS. Give him the bracers and a Flask of Supreme Power and he will give you what you need to summon Lord Valthalak in the Beasts Room in UBRS. Clear to the Beasts room. Kill the Beast. Summon Lord Valthalak. Kill Lord Valthalak and loot the quest item. TALK TO THE SPIRIT OF LORD VALTHALAK AND THEN AND ONLY THEN, return to the Ghost outside of BRS. He will send you back to the NPC where you started the entire quest chain (Ironforge/Orgrimmar) for your Helm and Breastplate.
Items you will need
In addition to making you go around and kill this, gather that, etc. the various NPCs also request a number of tradeskill items. On Test, everything necessary was in our inventory when we logged into the pre-made characters. The list of everything you will need is as follows:
Belt & Gloves
* 1 Delicate Arcanite Converter
* 4 Greater Eternal Essence
* 10 Stonescale Oil
o 40gold to Mux Manascrambler
o 50gold to buy a Quest Item: Fel Elemental Rod (or 40gold if you are not on the quest to buy it)
* Extra Goblin Rocket Fuel as needed
Shoulders, Boots, & Pants
* 3 Dark Iron Bars
* 3 Mooncloth
* 20 Enchanted Leather
* 4 Cured Rugged Hide
* 8 Large Brilliant Shard
* 4 Dark Runes
Helm & Chest
* 120gold to buy a Quest Item: Hallowed Brazier
* 1 Twilight Cultist Robe (Thottbot) (+ 3 others to get the 3 Abyssal Crest needed to get the Twilight Cultist Medallion of Station)
* 1 Twilight Cultist Mantle (Thottbot) (+ 3 others to get the 3 Abyssal Crest needed to get the Twilight Cultist Medallion of Station)
* 1 Twilight Cultist Cowl (Thottbot) (+ 3 others to get the 3 Abyssal Crest needed to get the Twilight Cultist Medallion of Station)
* 1 Twilight Cultist Medallion of Station (Thottbot) (i.e. 1 Large Brilliant Shard and the 3 sets of Twilight Cultist listed above)
* 1 Signet of Beckoning: Fire (or luck) (Thottbot)
* 1 Flask of Supreme Power