To start the Level 40 Thief Life Quest, speak to Fanny Love in Darkdale (X:348 Y:311), who, after paying her 2000 gold, will give you an Invitation to take to O'Shea in Collington (X:482 Y:458). After the cutscene, you will receive a Tome of Demonslaying and will be sent to kill rats in the following order: While a team is recommended (due to the high HP of the rats), only the team leader will receive credit for the battle. You will receive 20 Fame for killing each rat. After killing the last rat, return to O'Shea in Collington to receive your rewards.