Fiyr remains are an item found and used in the Shades of Mort'ton minigame. To obtain these remains, the player must kill a Fiyr shade, located in the underground tomb. To enter the tomb, the player needs at least a bronze shade key, obtainable by killing and cremating a Loar shade. However, players need a silver key from an Asyn shade, to actually reach fiyr shades. Fiyr shades can also be encountered during Temple Trekking (in the Mort'ton section), which yield Fiyr remains which may give silver keys.
To burn the Fiyr remains, first place magic or redwood pyre logs on a funeral pyre, followed by the Fiyr remains, then ignite the pyre with a tinderbox. This will grant the player Firemaking experience (see table), and 100 Prayer experience. Burning a set of Fiyr remains is a possible challenge given by Sherlock in master clues.
Fiyr remains will reward the player with either a silver or gold shade key, or some coins. Gold keys give unrestricted access to all areas of the shade tombs and can open gold rewards chests, while silver keys give access to all areas up to the Fiyr area in the north-west corner of the tombs and can open silver rewards chests.
Completing the Morytania Diary 3 offers 50% more Prayer experience, and completing the Morytania Diary 4 offers 50% more Firemaking experience.
Players may only use Magic or Redwood pyre logs to burn Fiyr remains.
Drop rates estimated based on 47,744 cremations from the Drop Rate Project, unless otherwise cited.
For an exhaustive list of all known sources for this item, see here