After reaching Heart of Azeroth Level 65, I was greeted at the Chamber of Heart with two new quests. One of them starts with Kalecgos who sends you to the Twilight Highlands. There, a Vermillion Holdout scenario requires you to reduce the enemy threat from the Void-Twisted invaders.
After defeating Vexiona, Alexstrasza visits the Chamber of Heart to empower the Heart Forge with Tempered Scale of the Scarlet Broodmother. This adds the Crucible of Flame power.
Click the title of the videos to access Fullscreen (1080HD).