Gom Jabbar

Destroy target unit.
The gom jabbar is a thin needle attached to a thimble,
allowing it to be worn on the finger. It contains a
deadly poison, which the Reverend Mother Mohian, a
powerful Bene-Gesserit, uses in Dune to determine
whether Paul, the protagonist, is a human. She warns
him about "the death so swift it's like the fall of the
headman's axe" (Herbert, 13).