Talk to Dark Fang (the Lighthaven dragon) and say Tomb Raider to him.
He will assign you to kill Tomb Raider. You can find him at the cemetery mausoleum.(Alsoknown as the Arakas Tomb) Kill him and return to Dark Fang.
Say Tomb Raider to him and you will be rewarded with 5.000 Experience Points.
Gain :
Note 1: An easy way to kill Tomb Raider is to let the Mummies hit him. When he becomes red attack him and kill him.
Note 2: If someone else has killed the Tomb Raider, you must wait about 30 minutes before he reappears.