Showdown

64,18 is the cooridinates..seems nobody has mentioned it

The quest chain:
1. Thunderlord Clan Artifact - http://www.wowhead.com/?item=30431 (Drops from the Bladespires)
2. Thunderlord Clan Artifacts - http://www.wowhead.com/?quest=10524 (Get the Arrow, Drum and Tablet)
3. Vision Guide - http://www.wowhead.com/?quest=10525 (Right-click the fragment and see where the last artifact is.)
4. The Thunderspike - http://www.wowhead.com/?quest=10526 (Go to the place show in the vision. Kill the guy guarding the spike)
---Rewards:
---Thunderlord Scalpel - http://www.wowhead.com/?item=31475
---Slow Death Dirk - http://www.wowhead.com/?item=31476
---Wand of the Ancestors - http://www.wowhead.com/?item=31474
5. The Spirits Have Voices - http://www.wowhead.com/?quest=10718 (Talk to the ghost leader)
6. Whispers on the Wind - http://www.wowhead.com/?quest=10614 (Talk with Leoroxx)
7. Reunion - http://www.wowhead.com/?quest=10709 (alk with Rexxar)
8. On Spirit's Wings - http://www.wowhead.com/?quest=10714 (Go to the ogres and use the whistle)
9. Baron Sablemane - http://www.wowhead.com/?quest=10783 (He's at the arena)
10. Into the Churning Gulch - http://www.wowhead.com/?quest=10715 (Kill random crust bursters for poison)
---Rewards:
---Bloodboil Poison - http://www.wowhead.com/?item=31535
11. Baron Sablemane's Poison - http://www.wowhead.com/?quest=10749 (Take the poison to Rexxar)
12. The Smallest Creatures - http://www.wowhead.com/?quest=10720 (drum up a marmot to poison the kegs)
......Side Quest......
...Crush the Bloodmaul Camp (From Tor'chunk Twoclaws) - http://www.wowhead.com/?quest=10784 (Kill ogres while you're poisoning kegs)
......Side Quest......
13. A Boaring Time for Grulloc - http://www.wowhead.com/?quest=10721 (Use the whistle, grab the sack, laugh)
14. It's a Trap! - http://www.wowhead.com/?quest=10785 (We can't stop here! This is bat country!...Talk to rexxar, again.)
15. Gorgrom the Dragon-Eater - http://www.wowhead.com/?quest=10723 (Use the trap at the altar)
---Rewards:
---Fanged Axe - http://www.wowhead.com/?item=31542
---Whistling Sword - http://www.wowhead.com/?item=31541
---Adjucator's Staff - http://www.wowhead.com/?item=31543
......Side Quest......
...Slaughter at Boulder'mok (From Tor'chunk Twoclaws) - http://www.wowhead.com/?quest=10786 (Kill more ogres)
......side Quest......
16. Prisoner of the Bladespire - http://www.wowhead.com/?quest=10724 (Kill more ogres, Use the whistle, profit)
17. Showdown - http://www.wowhead.com/?quest=10742 (Summon Rexxar at the altar and kill Goc)
---Rewards:
---Tourmaline Crown - http://www.wowhead.com/?item=31546
---Oilcloth Breeches - http://www.wowhead.com/?item=31545
---Leonine Breasplate - http://www.wowhead.com/?item=31549
---Clefthoof Leggings - http://www.wowhead.com/?item=31544
---Malefactor's Eyepatch - http://www.wowhead.com/?item=31547
---Blackened Chestplate - http://www.wowhead.com/?item=31548

If someone wants to go through all that and calculate the XP involved...I'm guessing about 1/4 of a level at 69.

A guide to completing the whole chain detailed in the first comment:

1) First of all fly straight to Bladespire Hold and kill ogres here. They will drop [item=30431], use this to
begin the first part of the chain.

2) Collect the artifacts described. They can be found at the following co-ordinates:
/way 41, 52
/way 40, 58
/way 41, 46

3) Fly to Rokgah Bloodgrip (/way 51.8, 58.4) and hand that in. He will give you then give you
Vision Guide and an item called [item=30481]. Use this while standing beside him and just wait for it
to do it's thing. Hand it in and take the quest The Thunderspike.

4) Fly to the cave (entrance co-ordinates are /way 42.5, 83.4) and run to the end of it. Click the shiny
spear and kill the ogre that spawns on top of you. Return to Rokgah. When you hand it in a Garm
Wolfbrother will appear beside you and offer you The Spirits Have Voices. Take it and hand it into Rexxar who
is just a few yards away (/way 51, 58).

5) Rexxar will then give you Whispers on the Wind. Fly east to Leoroxx (/way 75.2, 60.9) and hand it in.
Collect Reunion and return to Rexxar. He will then give you On Spirit's Wings, accept it and fly
north (/way 58.11, 33.53). Use [item=31128] in your bag and summon the spying bird right on top of
the Taskmaster and Soothsayer. Return to Rexxar.

6) After handing that in, he will offer you Baron Sablemane. Fly north again and hand that in (/way 53.3,
41). Accept the Baron's quest and travel over to the Burning Gultch (/way 49, 43). Kill [npc=21381]s
and loot them. Return to Baron Sablemane and accept his next quest Baron Sablemane's Poison.

7) This is more or less the second half of the chains leading up to Showdown. Deliver the Baron's
poison to Rexxar back at the Thunderlord Stronghold and then accept The Smallest Creatures. For this, fly
north and use [item=31141] at the Marmot Den (/way 56.46, 29.24). After taking control of one of
these little creatures, use it to poison the barrels of alcohol found at:

/way 55.36, 28.27
/way 55.25, 25.95
/way 55.96, 23.04

*Remember that the Marmots can aggro mobs, so avoid them. Use stealth on your pet's action
barand you should be able to sneak around everything. The Drum has a 6 minute cooldown so it's a
pain if your marmot dies.

8) Hand that in to Rexxar and collect A Boaring Time for Grulloc. Fly over to /way 60, 47 and let "Huffer" loose by
clicking on [item=31350] in your bags. When Grulloc has been distracted by the Huffer collect
[item=31349]. Take this to Baron Sablemane.

9) Accept It's a Trap! and take the trap to Rexxar. After handing that in he will give you the quest
Gorgrom the Dragon-Eater. Fly northeast to /way 30, 22 and kill 3 ogres, loot their heads and place them at the
alter in the middle of that open area. Set the trap (found in your bags) on top of the alter and wait for
Gorgrom. Once this is done, return to Rexxar.

10) Second last quest! Pick Prisoner of the Bladespire up from Rexxar and fly north again to /way 66, 22 and kill
ogres and loot the [item=31755]. Then use [item=31144] and the spirit will fly up and release the
Wyvern from its cage. Return to Rexxar to collect the quest you've been waiting for...

11) Collect Showdown and head to /way 64.15, 18.5 . Use [item=31146] here at the Alter of Goc
then kill him. Finally, return to Rexxar at Thunderlord Stronghold and collect your well deserved
reward!