This quest is not available in game.
Bring the following to Falrin Treeshaper inside Dire Maul: 1 Jeering Spectre's Essence, 4 Dark Runes and 8 Large Brilliant Shards.
I can place the enchantment you require on the banner quite easily, <name>. Unfortunately I don't have the materials I need as it is very rarely that someone asks for this sort of charm.
I will require the essence of one of the Eldreth ghosts that haunt these halls, a handful of Scholomance dark runes and some large brilliant shards. Bring me these reagents and I shall perform this task for you.