Take the Scourge Gryphon (51,35) back down to Death's Breach. Turn in The Scarlet Apocalypse to The Lich King at (53,36) and get An End To All Things... Use the [Horn of the Frostbrood] to use ride your Frostbrood Vanquisher. Ride south to New Avalon (57,60).

Hold the right mouse button to aim to and use ability (1) Frozen Deathbolt to kill soldiers and ballistas. You can avoid most of the damage done to you by staying high in the air or moving constantly. If you run low on health or mana, fly down to the ground within 15 yards of a Scarlet Soldier and press (3) to use Devour Humanoid to refill your life and mana. Fly back into the air to minimize any damage you may take.

On your return trip back to The Lich King, stop by the Plague Cauldron at (56,51), dismount by clicking on the red arrow at the very right and turn in any remaining [Crusader Skull] for More Skulls For Brew to get additional [Noth's Special Brew]. You won't be able to obtain any more of these after this point.

When you are done or if you're attacked while dismounted, use your [Horn of the Frostbrood]

Return to The Lich King at (53,36), dismount by clicking on the red arrow at the very right and turn in your quest. Take The Lich King's Command and go northwest to the cave entrance at (49,28). Travel through the cave to The Noxious Glade and then to Browman Mill at (34,30) and turn in your quest. Take The Light Of Dawn. If the event is starting soon, wait for it to start, otherwise begin the countdown by speaking with Highlord Darion Mograine

It's possible that the The Light Of Dawn event is already taking place or completed when you arrive, if you want to see the full scripted encounter (an epic battle with scripted story), wait a few minutes for the next event to start. Go back to Browman Mill and wait for Highlord Darion Mograine to reappear and speak with him to begin the event.

You will gain The Might of Mograine so have fun and don't worry about dying and enjoy this truly epic quest! Turn in The Light Of Dawn when the event concludes and take Taking Back Acherus. Use your new Death Gate spell to return to Acherus. Turn in the quest and take The Battle For The Ebon Hold.

Go ahead and train your level 58 spells (Blood Boil, Chains of Ice) from Mograine when you are back in Acherus. For your last 4 talent points, I suggest Blood Gorged 4/5.

Take the pink teleporter ahead to Upper Acherus and kill any 10 Scourge and then Patchwerk in the center of the room. Pull Patchwerk to the respawning portal guards so you don't have to worry about adds and to make this fight easier. Return back to Lower Acherus and turn in the quest.

• Alliance - Accept Where Kings Walk, your final quest and take the portal to Stormwind. Run to Stormwind Keep and speak with King Varian Wrynn at (79,38) to finish your last quest.
• Horde - Accept Warchief's Blessing, your final quest and take the portal to Orgrimmar. Run to the Valley of Wisdom and speak with Thrall at (31,37) to finish your last quest.

Congratulations on finishing the Death Knight starting zone!
I suggest using your Death Gate spell to return to Acherus. Vendor off any old items and repair (83,46) in Lower Acherus and stock up on [Corpse Dust] at (81,84) if you need any.

Go back up to Upper Acherus and take the flightmaster (83,50) to:

• Alliance - Menethil Harbor in Wetlands and take the boat to Theramore Harbor. In Theramore, do the Triage quest there so you can learn [Heavy Runecloth Bandage]
• Horde - Hammerfall in Arathi Highlands. Do the Triage quest there so you can learn [Heavy Runecloth Bandage]

Make your way to Blasted Lands in Eastern Kingdoms and to the Dark Portal at (58,58) and continue leveling in Outlands