The Mourner cloak is part of the mourner set. To obtain them, players must kill a level 114,120,or 124 Mourner on the path to Prifddinas. However, the Mourner will bring all combat stats down to 20, so it is recommended players bring a stat restore potion before fighting. They give no bonuses.
If you lose this cape, you can get another one by killing a level 114,120,or 124 Mourner again.
After completion of Plague's End, the mourner gear may be reclaimed from the mourner headquarters in West Ardougne. To obtain, enter the headquarters and descend the trapdoor. In the south eastern room is a chest from which the gear may be reclaimed.