Full 8.2 questchain:
To upgrade your Heart of Azeroth, you just need to do the 8.2 War Campaign starting with Horde: The Warchief's Order The Warchief's Order or Alliance: The Wolf's Offensive The Wolf's Offensive until you get to this quest.
Magni questline to unlock the Heart Forge:
1. Essential Empowerment Essential Empowerment
2. MOTHER Knows Best MOTHER Knows Best
3. A Disturbance Beneath the Earth A Disturbance Beneath the Earth
4. Take My Hand Take My Hand
5. Calming the Spine Calming the Spine
6. Dominating the Indomitable Dominating the Indomitable
7. A Friendly Face A Friendly Face
8. The Heart Forge The Heart Forge
9. Harnessing the Power Harnessing the Power
10. Horde: Back Out to Sea Back Out to Sea or Alliance: Back Out to Sea Back Out to Sea
11. Horde: Scouting the Palace Scouting the Palace or Alliance: Scouting the Palace Scouting the Palace <- (Not required for future Heart of Azeroth quests)
Level 54:
1. In Darkness, I Dream In Darkness, I Dream
2. Enter the Dreamway Enter the Dreamway
3. Shards of Emerald Shards of Emerald
4. Null the Void Null the Void
5. Don't Close Your Eyes Don't Close Your Eyes
6. We Must Go Deeper We Must Go Deeper
7. Before I Wake Before I Wake
8. The Stuff Dreams Are Made Of The Stuff Dreams Are Made Of
9. The Long Awake The Long Awake
Level 60:
1. Investigating the Highlands Investigating the Highlands
2. In the Shadow of Crimson Wings In the Shadow of Crimson Wings
Level 70:
PTR Info - quest not yet in WoWhead(might no longer be true):
https://ptr.wowdb.com/quests/56401-a-bolt-from-the-blue
Complete A Bolt from the Blue, after leveling your Heart of Azeroth to 70.