You can get Glory of the Raider by completing of Lich King Raid achievements in amount of 16:
The Dedicated Few
Make Quick Werk of Him
Momma Said Knock You Out
You Don't Have an Eternity
Gonna Go When the Volcano Blows
The Hundred Club
Denyin' the Scion
The Safety Dance
The Spellweaver's Downfall
A Poke in the Eye
The Twilight Zone
And They Would All Go Down Together
Just Can't Get Enough
Currently, you can no longer get Black Proto Drake mount for this achievement (but you can get the mount from the Black Market Auction house when it is up on your sever). However, you will receive points for this achievement, and addition of the list of achievements.
You can buy Glory of the Raider (10 player) achievement with ReinwinBoost team cheap, fast & safe.
It is a rather harder that it may seem, and we are there for you to do your game process easier.