Sadguru Sant Keshavadas taught us that the mantra is Om Eim Hrim Klim Chamunda’yae Vich’che Namaha. This is longer than the North Indian version, because it is in the Classical Sanskrit of the South. The shakti of the mantra is enhanced by the Om at the beginning and the Namaha at the end.
The goddess received her name by killing the demons, Chanda and Munda. She is one of the very fierce Tantric Devis of great protection.
Chanting this mantra brings protection and uniquely gives one strength. If you wake up with bad dreams, chanting chases them away.
I have sat in a meeting where all of the others wanted to take the whole time arguing with each other over minutia. I got bored and started chanting the Chamundi mantra silently. Within less than 5 minutes, the arguing stopped, and the others were able to get organized and do the tasks assigned.