為虎作倀

to act as accomplice to the tiger / to help a villain do evil (idiom)

as (in the capacity of) / to take sth as / to act as / to serve as / to behave as / to become / to be / to do / by (in the passive voice)

because of / for / to

tiger / CL:隻|只[zhi1]

worker / workshop / (slang) troublesome / high-maintenance (person)

to do; to engage in / to write; to compose / to pretend; to feign / to regard as; to consider to be / to be; to act the part of / to feel (itchy, nauseous etc) / writings; works

ghost of sb devoured by a tiger who helps the tiger devour others