Asyn shades lurk behind the black door in the Mort'tonshade catacombs dungeon. They initially appear as dark bluish moving shadows on the ground and then rise from the depths to attack or retaliate. On occasion they have also been known to leave their catacombs to attack trekkers and ramblers in the town above their dark burial place. Their remains can be cremated with eucalyptus, yew, or magic pyre logs. The Salve Amulet and Salve Amulet (e) work well on this shade which is very useful if shades are assigned for a slayer task.
You need to kill the level 80 shades and get the black key if you want to get access to the Asyns. You need 63 firemaking to cremate their remains and get the silver key to get access to the Fiyr Shades.