All Along the Watchtowers (Horde) Using the Beacon Torch, mark each tower in Andorhal; you will need to stand in the doorway of the tower to successfully mark it.
Once all four towers are marked, return the Beacon Torch to High Executor Derrington at the Bulwark, Western Plaguelands.
Blackrock Depths Horde Quest
Disharmony of Fire Enter Blackrock Depths and track down Lord Incendius. Slay him and return any source of information you may find to Thunderheart.
Winterspring Alliance & Horde
Are We There, Yeti? - (Step 3) Take Umi's Mechanical Yeti and scare her friends with it:
Legacki in Everlook (Winterspring)
Sprinkle in Gadgetzan (Tanaris)
Quixxil in Marshal's Refuge (Un'Goro Crater)
When you are done, bring the Mechanical Yeti back to Umi.
Into The Maw of Madness - (Step 2) Commander Mar'alith at Cenarion Hold in Silithus wants you to find his beloved Natalia. The information that you gathered points to Hive'Regal in the south as being the area in which you may find Mistress Natalia Mar'alith.
Do not forget to visit the dwarves at Bronzebeard's camp before venturing into the hive. They might have some additional work and advice for you.
And [Name], remember the Commander's words: "Do what you must..."
Eastern Plaguelands Alliance & Horde
The Battle of Darrowshire Place the Relic Bundle at the Darrowshire town square.
Prevent Davil Lightfire's death until the death of Horgus.
Prevent Captain Redpath's death until Redpath the Corrupted appears.
Defeat Redpath the Corrupted.
Speak with the spirit of Joseph Redpath when he appears at the town square, then speak with Pamela at her home.