Annah
Annah is an NPC who stands on the south side of the Green Line in Croatoa. He is not a contact, but it appears that he will grant a fifth costume slot as some point. His coordinates are (860.5, 0, 2252).
Currently, Annah appears as a scientist holding a scroll. It is rumored that the model will be replaced with a Cabal one.
When clicked, Annah says:
These are magical days indeed. To show your worth to the Ravenwing Cabal, I ask that you bring me some souvenirs of the season of the witch. These are costume pieces from some of the more popular costumes of the day. Bring me one Statesman Mask, one Lord Recluse Helmet, one Back Alley Brawler Gloves, and one Hamidon costume. If you do this, I will grant you access to another Costume Slot.