Requirements: You will need a Red Bead, a Yellow Bead, a Black Bead, and a White Bead to complete the quest.
Starting the quest-
To start Imp Catcher head to the Wizard Tower below Draynor and climb to the 3rd floor. Speak to Mizgog and ask him nicely for a quest. He will tell you that Wizard Grayzag had an army of imp's steal his things. Mizgog will ask you if you can retrieve his 4 magical beads, one black, one red, one white, and one yellow.
Get those beads-
To get the beads you have 2 choices. You can buy them from other players through trading or the Grand Exchange, but it isn't always easy to find someone with them. the second choice is to kill imps, you can do this anywhere they appear in Runescape. Eventually you will get all the beads from them in drops. once you have them, head back to Mizgog and speak to him. He will place them on a table and check that they are his. The test works and he rewards you with an amulet.
Rewards: 875 magic experience Amulet of Accuracy 1 Quest Point
