There are a number of synonyms that can be used for the phrase "lady-killing," which generally refers to a man who is particularly attractive to women. Some possible options might include "heartthrob," "charmer," "smooth operator," "ladies' man," "flirt," "seducer," "Don Juan," or "playboy." Each of these phrases carries slightly different connotations, so it is important to choose the right one depending on the context and tone of the piece you are writing. Overall, however, they all reflect the idea of a man who is able to attract and charm multiple women, often with ease.