Imp Catcher

Official quest description: The Wizard Grayzag has summoned hundreds of little imps. They have stolen a lot of things belonging to the Wizard Mizgog including his magic beads.
Release date: 16 February 2001
Start: Wizards' Tower, on the third floor, talk to Wizard Mizgog.
Difficulty: *****
Length: Short-Long
Members only: No
Requirements: None
Items needed:
A black bead
A yellow bead
A red bead
A white bead (or 3,000~ gold pieces).
Monsters to kill:
Imp (level 2) (not compulsory)
Spoiler warning: Plot and/or ending details follow.
Walkthrough
Make your way to the Wizards' Tower, south of Draynor Village over a stone bridge. Once there, you will know you are at the right place if you see level 9 Wizards. Climb the stairs, and go up to the third floor. Talk to Wizard Mizgog and ask him questions to find out he needs your help. He will tell you Grayzag's imps stole his beads and wants you to get them for him. He needs you to get:
A black bead
A yellow bead
A red bead
A white bead
To obtain the beads, you will have to kill Imps. Imps can be found almost anywhere in free-to-play. The best place, however, is on the island of Karamja. There are many imps here but are guarded by scorpions, so if you're lower than level 29, look for imps around the entrances Falador and the outskirts of Lumbridge. Keep killing imps until you have all four beads on you. The imps will sometimes teleport, making them annoying and hard to kill.
Another place to find and kill imps is the south entrance to Falador. Besides having around 3 imp respawns, it is a multi combat zone so a friend could help you.
Note that magic beads can be traded between players, and sold to stores.
Once you have all four beads, return to Wizard Mizgog and give them to him to finish the quest.
Unlike many other quest items, these beads are tradable, which means that if you have about 2,000 gp you can do this quest very simply by buying the beads on the grand exchange.