Magic Blood Effect
As used by special effects people use in Hollywood.
Made in two parts. Part a is a powder, Part B is a clear liquid.
First apply part A to on your skin. The powder blends with your skin tone and becomes basically invisible, especially from the stage.
Coat a stage knife or razor with the part B liquid.
When you draw the fake knife over your powder coated skin, it leaves a trail of dripping blood that looks exactly as if you had just made a cut in the skin.
This looks amazingly real. You're gonna love playing with this stuff.