I can place the enchantment you require on the banner quite easily, $N.  Unfortunately I don't have the materials I need as it is very rarely that someone asks for this sort of charm.$B$BI 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.