Slayer Codex

A Slayer Codex is the book used to record the souls of Slayer monsters that the player has captured. It is obtained from Faiza after achieving level 99 Slayer. The Codex is updated when a new creature's soul is captured in an ushabti and placed in the Chest of Souls, or when it is added to the player's personal Slayer dungeon.

Souls added to the Codex award 250 reputation each. Additionally, every 20 souls added to the Codex add a 1% boost to Slayer experience gained while wearing the Slayer helmet, up to 5% for adding 100 souls. After 50 souls are added, the Codex can be used to teleport to the Sunken Pyramid. New murals in the Sunken Pyramid are uncovered with 10, 30, 50, 70, 90, and 110 souls added.

The first ushabti of a creature that the player turns in gives them full experience, and the following ushabti of that same creature gives the player 25% experience. Turning in all souls at least once will complete the Slayer Codex, which will give a cumulative 1,522,375 Slayer experience.

Completing the Codex and having unlocked the red version of the Slayer Master title from Rush of Blood unlocks the golden Slayer Master (title) title.

There are currently souls to capture.

Slayer monsters
In order to fill the entire Codex, players will need level 117 Slayer (boostable) and level 115 Dungeoneering (which cannot be boosted). This does not include other requirements such as quests and tasks. Some monsters can only be killed when given to the player as a Slayer task (ex. Desert Strykewyrms).

For monsters that fall under one category, killing any non-boss monster will be eligible for the ushabti to capture its soul. The only exceptions to this are gemstone dragons, corrupted creatures, and soul devourers, who all have their own individual categories for the purpose of the Slayer Codex, and ascension creatures, as the Legiones bosses may be killed for a soul. When the ascension creature soul is captured it will be displayed as a random ascension creature when the check option is used on the ushabti.

Trivia

 * TzHaar and volcanic creatures are the only slayer categories not included in the Slayer Codex in any form, likely due to their souls being trapped in Tokkul.
 * A boosted Slayer level does not count towards the likelihood of getting a soul.
 * Players who had monsters added to the Slayer Codex prior to 26 June 2017 were retroactively awarded 250 reputation for each monster.
 * All grotworm souls are referred to as Mature grotworm souls when deposited in the Chest of souls.