Soul Eater Killing Sigil
From Super-wiki

Sam completes the sigil.
The Soul Eater Killing Sigil is a special sigil created by the Men of Letters as a means to kill the previously unkillable soul eaters. The sigil is made by using the blood of the person or persons creating it. It is then drawn in the home that the soul eater has invaded, as well as in the soul eater's nest, which requires a person to allow a soul eater to take his soul. The sigil inside the nest "sets the table," while the sigil on the earthly plane kills the soul eater.