1. Journey to the Assassin's Guild, found in moc_fild16 (205, 296), two maps South and two maps East of Morroc. The entrance to the guild is located near the center on the upper portion of the island.
2. Talk to the Guildsman NPC (in_moc_16 19, 33), who allows would-be Assassins into a room with another NPC as long as they are Thieves at Job level 40 or above.
3. Walk near the Guildsman at (in_moc_16 25, 90). After signing up, access to the next room will be granted.
