Fig.: a destructive or fatal relationship or action, undertaken with seemingly good intentions

That cookie TV commercial was the kiss of death to his career as a serious actor: now he's Mr. Cookie Jar for everyone

Quella pubblicità TV dei biscotti ha dato il colpo mortale alla sua carriera di attore impegnato: ora per tutti è Mr. Biscotto

Support from that leader who is hated by the people, was the kiss of death for the presidential candidate who, as a result, was not elected

Il supporto da parte di quel leader tanto inviso al popolo, è stato il bacio della morte per il candidato alle presidenziali che, di conseguenza, non è stato eletto

Plastics and seawater warming are going to be the kiss of death for coral reefs

La plastica e il riscaldamento delle acque marine saranno il colpo mortale per le barriere coralline

The term, which was previously known as “Judas kiss”, refers to the betrayal of Jesus Christ by his disciple, Judas Iscariot, who kissed Jesus as a way of identifying him to those who would arrest and put him to death. (Matthew 26:47-49)