fatal mistake, downfall
小さな音が命取りになります
Even the slightest sound could cost you your life.
— 道 (1954)
その時も時だあいつにとっちゃ命取りのあの事件が起こった
Then came the incident that would prove fatal for him.
— High and Low (1963)
命取りになる
It could be fatal.
— グッバイ、レーニン！ (2003)
その間違いが彼の命取りとなった。
That mistake cost him his life.