- Not to be confused with Mort'regar.
In order to destroy Icecrown Citadel, the gates in Icecrown must first be taken. This is why players of both the Alliance and Horde are sent to sabotage these gates, so the army can conquer the gates. These quests are either given by Koltira Deathweaver or Thassarian, depending on one's faction, and involve killing Pustulent Horrors and throwing their spines into plague cauldrons to turn the plague into corrosive acid (the latter is better for the troops than the first, according to the death knights), as well as taking out a powerful zombie, Coprous the Defiled.
After the player has completed these quests, the Death Knight quest giver deems the assault by the big army on the gate to be doable, and sends the player to Aldur'thar: The Desolation Gate.
- The name "Mord'rethar" might be derived from Mordor, the kingdom of Sauron in Lord of the Rings, considering the design of Icecrown Citadel seemed to have been inspired greatly by Barad-dûr and other dark citadels from the trilogy, and the Lich King's resemblance with Sauron.
- Patch 3.0.2 (2008-10-14): Added.