Blood Lamp by Mike Thompson.
Found through this article on MNN.com:
When designer Mike Thomspon asked himself, “What if power came at a cost to the individual?” he ended up creating the blood lamp as a statement on energy conservation. This single-use lamp requires a drop of blood to be activated—a personal sacrifice that will really make you think twice before turning on the lights. The lamp’s secret ingredient is luminol, the chemical forensic scientists use to check for blood, which glows blue when it reacts with the iron in red blood cells.
Phylacteries? Phylacteries. Blood magic.
This is totally what they do in Tevinter.
everything is blood magic and nothing hurts.