Death Knight Leveling Guide (55-56)
1) Go to Prince Valanar in Death's Breach [D] and turn in "The Scarlet Harvest". Get the four new quests in the town: "If Chaos Drives, Let Suffering Hold The Reins", "Grand Theft Palomino", "Death's Challenge", "Tonight We Dine In Havenshire". Win 5 duels with Death Knight Initiates in the town to complete "Death's Challenge". Turn it in to Olrun the Battlecaller.
2) Head to [E]. Kill 10 Scarlet Crusaders, kill 10 Citizens of Havenshire, and collect 15 Saronite Arrows off the ground. Use the letter atop the mailbox at (55,46) to complete "Abandoned Mail".
3) Steal a horse at [F] and ride it back to Death's Breach.
4) Use the action buttons to gain speed and to turn in the horse at [D] to complete "Grand Theft Palomino". Accept "Into the Realm of Shadows".
5) Go to [F] and kill a Dark Rider of Acherus.
6) Ride the Deathcharger back to town [D] and turn in "Into the Realm of Shadows", "Tonight We Dine In Havenshire", and "If Chaos Drives, Let Suffering Hold The Reins". Accept "Gothik the Harvester" then turn it in and accept "The Gift That Keeps On Giving". Don't forget to spend your new Talent Points!
7) You'll find your new mount, Acherus Deathcharger, in the Pets tab under Character Info (shift-P). Ride it to [G] and use Gift of the Harvester on Scarlet Miners until you have 5 Scarlet Ghoul minions.
8) Go back to Death's Breach [D] and turn in "The Gift That Keeps On Giving". Accept "An Attack Of Opportunity". Turn it in and accept "Massacre At Light's Point".
9) Go to [G] and use the Mine Car at (58,33). Kill 100 Defenders with the Scarlet Cannon. Use the Pulse ability when the mobs are too close to shoot. When finished, use the cannon to call a gryphon that will fly you back to town.
10) Turn in "Massacre At Light's Point" at [D] and accept "Victory At Death's Breach!" You should be level 56 at this point. Use a Scourge Gryphon to fly up to Archerus.
11) Turn in "Victory At Death's Breach!" at [C] and accept "The Will Of The Lich King". Don't forget to train before you leave. Ride back down on a Scourge Gryphon.
12) Turn in "The Will Of The Lich King" at [D] and accept "The Crypt of Remembrance".