WoW BFA Guide: How to Unlock Siege of Boralus and King's Rest Mythic Dungeons
World of Warcraft: Battle for Azeroth has two dungeons that can only be done on Mythic difficulty. The dungeons must also be unlocked before you can do them. Each faction unlocks them in a different way and if you play both factions, you must unlock them separately for each.
There will be small story spoilers when explaining how to unlock these dungeons.
Once you unlock them on one faction, all your other characters on that faction can enter the dungeon without doing the required unlocks. I'm going to explain how to unlock them on each faction, and show the entrances to each dungeon, since you must walk into Mythic dungeons.
Alliance Mythic Dungeon Unlocks
How to Unlock Siege of Boralus
Alliance players can unlock the Siege of Boralus dungeon by doing the main storyline.
This requires you to complete all the story chapters of Tiragarde Sound, Drustvar, and Stormsong Valley. Once you've done this, you will get a new quest from Tiragarde Sound that starts a new questline to find and free Jaina.
This involves doing multiple dungeons and other quests, but eventually leads to unlocking the dungeon
and getting a quest to complete it. When you complete the Siege of Boralus quest, you end the questline.
How to Unlock King's Rest
This requires Alliance players to do the War Campaign and increase their 7th Legion faction rep. There are 8 total chapters to the war campaign and you unlock King's Rest during the 7th chapter. As long as you do the previous missions, this will unlock once you reach 7,500 rep in the Honored rank.
During the mission, you will get a single quest that unlocks King's Rest automatically.
Horde Mythic Dungeon Unlocks
How to Unlock Siege of Boralus
Just like unlocking King's Rest for the Alliance, this requires Horde players to do the War Campaign and increase their Honorbound faction rep.
When you reach 7,500 rep in the Honored rank with Honorbound, and do the previous missions, Siege of Boralus will unlock during the 7th chapter of the war campaign.
How to Unlock King's Rest
For Horde players, this dungeon requires you to complete the main storyline for Zandalar. You must complete every story chapter in the Zuldazar, Vol'dun, and Nazmir zones. After that, you will get the Blood Gate questline that takes you back to Nazmir.
After you complete the final scenario, King's Rest will automatically be unlocked.
That's all for this guide on unlocking Siege of Boralus and King's Rest in BFA. Let me know if you have any questions!