You see A Ghostly Sage
Location
In the Pits of Inferno under the Plains of Havoc.
Notes
This NPC is located at the end of the Pits of Inferno Quest, just before you use Key 3700 to access the reward room. He seems to be interested in trading something - something you usually wouldn't bring to the Pits of Inferno.
He wants God Flowers. After you give them to him he will give you a hint on how to get Key 3700, which is needed to enter the reward room.
He will teleport you out of the Pits of Inferno's main room if you say "teleport" to him. You will arrive in the Slime cave under the Plains of Havoc.