Another Icelandic magical sign deserves special attention, since it is reported to give the power to become invisible. Hulinhjálmur (‘helm of disguise’) has to be drawn on a piece of lignite (brown coal) and then pressed against one’s forehead. The most complicated part is the preparation of the ink. One has to collect three drops of blood from the index finger of one’s left hand, three from the ring-finger of one’s right hand, two from the right nipple and one from the left nipple. Then the blood must be mixed with six drops of blood from the heart of a living raven and melted with raven’s brains and pieces of human stomach. This kind of magic was used as the best protection against enemies.