Hanuman assumed Panchamukhi or five-faced type to kill Ahiravana, a robust rakshasa black-magician and practitioner in the dim arts over the Ramayana war. Ahiravana, brother of Ravana, had taken Lord Rama and Lakshmana to netherworld as captive, and the only way to destroy him was to extinguish five lamps burning https://directoryark.com/listings13276866/about-mantra