How to Solve
The wyvernsource guide skips through all the travel and npc finding to quickly complete the quest. WyvernSource Guide
This guide will walk you through the entire quest and help you find the NPCs needed to solve the quest as it was written. This requires going across the Wyvern world map several times for information, so many people opt to skip this.
This quest starts at the Zoo. Enter the Zoo headquarters to talk to Kristina about a quest. She will tell you that there is a problem with the magical creatures section, and you should go through the secret entrance in the northwest corner of the aviary and ask Tor about it. She also comments that the panda-patterned floor was made by a dwarf from Varak.
There is a map of the zoo across the path from Zoo Headquarters. Examine (not apply) the sign to see the map. The aviary can be found by going north to the Arctic zone and then east, past the wolves. The secret entrance is a wall you can walk through behind some trees.
Walk past the office/storage rooms until you find a Mage in green robes, standing next to a blast crater behind the magical animals exhibit. This is Tor. He will explain that the magical orb that powered the magical cages wore out, and that it needs to be replaced. He is stuck there, keeping the creatures contained in place of the orb. He says no one knows where it came from, but he suggests asking Garignor in New Verden about it.
Garignor's house is a mansion on the east side of New Verden, north of the yellow pavilion. Inside, you will find Garignor, a Mage in red robes. He will give information about the Garignor's Amulet quest, which is separate and not necessary to complete for the Zoo quest. He says he doesn't know anything about the Zoo Orb, but someone named Devra might know of it. Last he heard, Devra was in Ghanar Fyr, but that was many years ago.
Ghanar Fyr is an island on the west side of the world map, between the claw and chin of the wyvern. Tim the Miller, who is found in the windmill building, will know about Devra. He will say that she moved to Havishfel, the island west of Ghanar Fyr a few years ago to serve as their mage.
In Havishfel, find the magic shop south of the old Mage's guild. Inside on the first floor, Sparrowhawk the Mage will tell you that she has gone to visit her brother in Stensele.
Stensele is on the base of the tail of the dragon. The smaller of the two houses along the east wall of Stensele (northeast of, ironically, the Stensele zoo) belongs to Jiron, Devra's brother. He says she is watching his shop right now.
Devra is on the first floor of the magic shop. She says she has studied the orb, doesn't know how it was created, but that it was definitely made by the elves, and that it is very old.
A random drunk pirate in the tavern will also mention that elven city is surrounded by yellow aspen trees.
Sithra and the Rose
Find the elf city Almien, north of Stensele. If the elf guard is blocking the bridge, the password to get across is "mellon" which means "friend" in elvish.
The person you are looking for is the Elf Queen's mother. She is in her room on the 2nd floor of the elfish Royal Hall. She will tell you that she made the orb many milennia ago, and that the humans at the zoo probably didn't take proper care of it. She will create a new one for you if you can find a certain rose bush for her to plant in the royal gardens.
The rose was given to her by a travelling rakshasa named Sithra, who came from the north, but is heading first to Jbel, and then home to Rakshasa Haryma.
Jbel is on the tail of the wyvern, a village that is part of the larger desert city of Bandar Gaah. Enter Bandar Gaah and walk west, following the path across the bridge in the next map. The shopkeeper of the general store remembers Sithra. He will tell you that she was looking for a rare rose only found in Varak. I'm not sure if there is anything to find in Rakshasa Haryma (I have not found anything) so at this point it's time to move on to the dwarf town Varak.
Find the general store in Varak. Ask the shopkeeper about a rose, and he'll say he's out of stock: he sold his last one to a rakshasa. He says he gets them from a valley to the west. Note that conveniently, there is also a portal to Almien in the bottom right corner (costs 600gp).
Find the map west of the general store between the mountains. Keep going west and you will find a castle guarded by a giant. Enter the castle and keep going west until you find the garden in the back. There is a rose bush in the middle of a pond. Type "swim on" to swim across the pond to get the rose bush. Make sure to disable it again ("swim off") when you're done so you don't accidentally jump in the water and drown some time later.
A new orb
Return to the Elf Queen's mother and give her the rose bush. She will give you a new orb, and tell you to tell the zoo to take better care of this one.
Return to Tor and give him the orb of energy. You will complete the quest!