Candrian Illborne is a planewalker resting in the Smoldering Corpse Bar. He has traveled widely throughout the planes, and is thus a great source of information on many things. He knows much about the portals around Sigil, since they are his primary means of transportation.
Negative Token Edit
Candrian can help Ingress find the portal leading back to her home world (750 XP upon returning to him).