Antonyms for the phrase 'took prisoner' include words like 'release', 'free', 'liberate', 'discharge', 'let go' among others. These words denote the opposite of being confined or held against one's will. They signify the act of setting someone free rather than imprisoning them. 'Release', for instance, means to let go of someone or something, while 'free' describes the state of not being enslaved or confined. 'Liberate' refers to the act of freeing someone from oppression or captivity. 'Discharge' implies the release of someone from confinement or military service. In essence, the antonyms for the phrase 'took prisoner' are words that represent the opposite of captivity, confinement or imprisonment.