There is a new quest in World of Warcraft 7.2.5 (build 24026) named The Spoiled Sample. This item is looted from the Grand Challenger’s Bounty chest — this is the chest you loot from on Tuesdays at your Class Hall, after completing Mythic+ dungeons.
The quest is then turned in at the Blacksmith building (next to the Obliterium forge) in Dalaran. Talk to Arcanomancer Vridiel who then gives you a quest named: Unsettled Power. The reward for completing it is the Stabilized Titan Essence — which Infuses a Legion Legendary item with greater power, raising its item level to 970.
Note: The Writhing Essence x 50 is a grind drop from The Nighthold raid.
This quest will be highly sought by those who haven’t yet completed the Legendary Quest at the Broken Shore Mage Tower, to get that extra oomph needed to complete the class trial.
Arcanomancer Vridiel: The release of the energy previously trapped in the Nightwell has… complicated the influence of Aman’Thul scattered around the Broken Isles. Sadly, the results of all of my previous work has been invalidated, much as the contents of this vial. I must understand what caused this change! Please, bring me more samples so that I may continue my work. Naturally, you will be the beneficiary of any breakthroughs I may find.
Bring 50 Writhing Essence to Arcanomancer Vridiel.