The Rhynn Lanthorn was a magical lantern held by the elves of Suldanessellar. It had the power to reveal things behind even the most powerful illusions. When Irenicus was attacking Suldanessellar, he hid its entrance with illusions to prevent Elhan and his troops from entering. The Lanthorn was capable of seeing through the illusions, so he had Bodhi steal it and hide it in Athkatla. Only when it was recovered were the elves able to get back into the city.