Istelli is a Cerulean Nymph, an ancient race blue skinned women forgotten by most residing in the Village of Polidora. They are the only race to possess the ability to create potions of warding, granting resistance to an element depending on the potion. You are sent to gather a plethora of flame ward potions, but Cerulean Nymphs have no use for your currency. (Part 11 of Aldenhigh Adventures Act 1.)