Slayer Codex

A Slayer Codex is a book used to record the souls of Slayer monsters captured. It is obtained from Faiza with 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.

Every soul added to the Codex also awards 250 reputation. Additionally, every 20 souls added to the Codex adds a 1% boost to Slayer experience gains 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.

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 cumulative Slayer experience equal to 1,442,875 experience.

Completing the codex and owning all four Rush of Blood titles unlocks the Slayer Master (title) title.

Slayer monsters
In order to fill the entire codex, players will need 117 Slayer (boostable) and 115 Dungeoneering (which cannot be boosted). This does not include other requirements such as quests and tasks. Some monsters can only be killed while on their respective slayer task.

For monsters that fall under one category, killing any non-boss monster will be eligible for the ushabti to capture its soul. The only exception to this are gemstone dragons, corrupted creatures and soul devourers.

Trivia

 * TzHaar and volcanic creatures are the only slayer categories not included in the codex in any form, likely due to their souls being trapped in Tokkul.
 * Gemstone dragons, corrupted creatures and soul devourers are also not included as categories of their own, as each monster belonging to them has been separated into their own category for the purposes of the codex.
 * A boosted Slayer level does not count towards the likelihood of getting a soul.
 * Players who had monsters added to the Codex prior to 26 June 2017 were retroactively awarded 250 reputation for each monster.