Moxibustion is a very special medicine--the most Yang (warm and energetic) substance available to us. The mugwort plant, from which moxa is derived, is used in European traditions for protection, dream stimulation, and purification (when burned). In East Asian medicine, the fine hairs on the surface of mugwort leaves are ground and processed to create a fluffy substance that gives the body enormous energy when burned on appropriate points.
Its medicinal uses are numerous, and include fatigue, arthritis, common cold, "cold conditions" which benefit from the plant's warmth, spontaneous sweating, muscle pain and weakness, paralysis, and many more. Moxibustion increases platelet count, red blood cell count, white blood cell count, and hemoglobin, so I have used it to successfully treat immune deficiency and blood disorders.
One study burned many different herbs on the surface of a watermelon. Mugwort is the only herb that penetrated the entire body of the watermelon with a dark line.