Amulet of Accuracy, 875 Magic experience and 1 quest point
Before I start this guide, I thought I should mention that I absolutely HATE this quest. I'll tell you why in a moment.
To start this quest, speak to Mizgog on the top floor of the Wizards tower (South of Draynor Village). He'll tell you about the quest.
The rest is simple.
Go kill imps and collect 4 different coloured beads.
When I say "it's simple", I mean it's simple, in THEORY. You can spend HOURS killing imps and be unlucky enough to not get all the beads you need, or it could take 10 minutes, it all depends on how lucky you are. All you have to do is collect beads, so if you get bored with killing them, only kill them when they are near you when you're doing somehting else.
One you've got all the beads, take them back to Mizgog for your reward.