a strip of metal, going from the highest point of a building to the ground, that prevents lightning from damaging the building by taking the electricity to the ground before it can reach a dangerous level

someone or something that takes all the blame or criticism in a situation, although other people or things are responsible too

In a harsh economic climate, pay rises for politicians have become a lightning conductor for criticism. 在经济状况十分严峻的情况下，给政客涨工资这一举措便成了众矢之的。