Ratsbane

The Gadfly’s venom, fifty times distilled, Is mingled with the vomit of the Leech, In due proportion, and black ratsbane, which That very Rat, who, like the Pontic tyrant, Nurtures himself on poison, dare not touch;—

Before him set the grim baron, with a face worthy of the father of such a daughter, and looking daggers and rat's bane.