Glarial's amulet is an item used in the Waterfall Quest. It grants access to the Waterfall Dungeon. The amulet is not needed if the player has completed the Waterfall Quest; otherwise, it must be worn or present in the player's inventory, to avoid a severe damage penalty. If a player attempts to enter the dungeon without the amulet, they will be swept away, taking some damage and ending up downstream from the door.
If lost, you can recover the amulet in the western chest inside Glarial's Tomb. To enter the tomb, you must be carrying Glarial's pebble, and have no armour, weapons, or runes equipped or in your inventory. You can get duplicate amulets by dropping the amulet, getting a new one, and picking it up again. Beware of the moss giants in the tomb.