Darkfire

A flame that burns with heat, but no light. There are several ways to start darkfire, including friction in specific woods grown in the land of Umbra, but the easiest way is generally with a drop of blood from someone either of the Darkness or of the Kin with Darkness in their blood. The chemical qualities of that blood can, with certain incantations, alter the makeup of flammable goods, allowing it to catch with darkfire instead of ordinary flame.