Death Knight Leveling Guide (57-58)
1) Use your Scourgestone to recall to The Ebon Hold. Enter the transporter and turn in the quest to Highlord Darion Mograine [C]. Accept "The Scarlet Apocalypse". Train before you fly to Death's Breach.
2) Turn in your quest to The Lich King's new location [D]. Accept "An End To All Things…" and use the Horn of the Frostblood in your inventory to ride a Frostblood Vanquisher.
3) Fly south to New Avalon [K] and use Frozen Deathbolt to kill 150 Solders and 10 Scarlet Ballistas. Go low to the ground and use Devour Humanoid near a Soldier to regain health.
4) Fly back to The Lich King [D] and turn in the quest. Accept "The Lich King's Command". Head NW through the cave.
5) Ride to Highlord Darion Mograine at [Q] to turn in the quest and accept The "Light of Dawn". If he is not there, you will have to wait until the next cycle for him to respawn. Make some bandages and spend talent points in the meantime!
6) Go to Light's Hope Chapel [R] and help the Scourge defeat the Argent Dawn. Talk to Mograine to complete the quest. You will be ported to the Open World version of Acherus.
Train and go to a Runeforge to affix a rune to your new weapon. Next stop: Outlands! Talk to the flightmaster to fly to Swamp of Sorrows and enter the Dark Portal in Blasted Lands.