nail in the coffin

Translations
гвоздь в крышку гроба
The scandal was the final nail in the coffin for his political career.
Скандал стал последним гвоздем в крышку гроба его политической карьеры.
Definitions
A nail in the coffin refers to an event or action that contributes to the failure or demise of something, often seen as a final or decisive blow.