Female narcissists harm others by relational aggression. This means they will deftly cut someone out of their lives, usually another woman. At the same time, the aggressor builds a solid social circle around herself.
The banished person loses her social standing. The narcissist knows this, and she stops at nothing to make sure the woman she's targeting becomes an outcast.
Everyone involved is forced to choose between the group led by the narcissist, or the solitary player the narcissist is punishing. Most people find the former option much more attractive. That's because we're social beings with a deep need to belong.
A few people will straddle the fence, as the narcissist attempts to drag them over to her side. One by one, they fall and, eventually, become her allies.
If this is a group of mothers, the stakes are high. Not going along with the narcissist's agenda means you, and your children, could also be cast aside. This means no more play dates, sleepovers and birthday party invitations. Even the most well-meaning Mom will have a hard time resisting the pull, given the circumstances.
For the target, this is traumatic. She will suffer social isolation, and she will watch, as her children are also left without any "friends." She will grieve for the lost relationships, but, most of all, she will worry greatly how this will affect her children, now sitting on the sidelines right along with her.
I recently read a magazine article about a suburban mom targeted in such a way, after moving into a very nice neighborhood. Once this happened, she begged her husband to sell the house so they could relocate.
Actually, when things turn toxic among a group of mothers, all the children suffer. The narcissist's offspring have it particularly rough, as being raised by someone with a moral disorder is no picnic. The bystanders, who do nothing to help the target, and accept the fact she's being mistreated, send a horrible message to their own children, of just how not to behave.
Unfortunately, everyone suffers when narcissistic abuse goes unchecked.
So, what's the solution? I don't have the answer, but I do hope that raising awareness of malignant narcissism will help more people see through these sick mind games, so people can see them for what they are and decide not to play.