Use the Hyldnir Harpoon to defeat 10 Hyldsmeet Drakeriders at the Temple of Storms. Use the Hyldnir Harpoon on a Column Ornament to exit the Drakkensryd and speak to Thorim when you've succeeded.
10x Hyldsmeet Drakerider Defeated
This is it. You've passed all the tests of the Hyldsmeet... all but one. You've risen among our sisters' best and fiercest.
The final test is at hand. The Drakkensryd - the true test of a Hyldnir's worth and warrior spirit. It'll be you, your riding drake, a chained harpoon and a score of your sisters vying for dominance.
Show no quarter. None will be expected.