The Nether Amulet is an amulet added by the Harken Scythe mod that can only be used in the Nether. It will teleport you back to your bed/resting place when used. It costs 5 souls from a Soulkeeper and 10 blood from a Blood Vessel to do this.
To use the Nether Amulet, hold down your right mouse button when it is selected. You will have to hold it down for about 10 seconds before it teleports you. Teleport progress is shown by the item's durability bar.