Bertha is a large lady and a former opera singer. She is a contractor that is able to control the resonance of sound. By resonating a frequency that is the inverse of a target's resonance frequency, she can destroy a target.

This can also cause other body problems, such as a heart attack, by matching the hearts resonance frequency.

Bertha's remuneration is to place something in her mouth and then vomit it out; for example, she is shown paying by eating a handful of cigarettes and then spitting them up. Its does not have to be cigarettes but she recounts her past to Itzhak about how she had a baby, who unfortunately choked to death while ingesting one of Bertha's dropped cigarettes.

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