Kumba is to be found generally north east of the Captain of the Guard. He dropped his amulet and a spider ran down a hole with it. If you return it to him, he will give you his much cherished "Moth Eaten Cloak". Start killing spiders until you receive a message in your chat window that you've found his amulet. If you miss the message, which sometimes happens in the heat of battle, go back and talk to Kumba. If you did find his amulet, he'll tell you and give you that lovely cloak! (It does look cool).