Slayer Codex - The RuneScape Wiki

The 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. Removing a monster from the slayer dungeon will not remove the soul from the Codex.

Slayer training, Old School RuneScape Wiki

Fremennik Slayer Dungeon, Old School RuneScape Wiki

Slayer Codex, RuneScape Wiki

Black dragon - The RuneScape Wiki

Slayer - The RuneScape Wiki

Greater Barge ability codex - The RuneScape Wiki

Slayer Codex, RuneScape Wiki

Slayer Codex - The RuneScape Wiki

Nihil, RuneScape Wiki