Ketu Yantra is to appease the planet Ketu. When Ketu is malefic, the use of Ketu Yantra is very benefic and favorable.Ketu Yantra is embossed on Copper plate and indicates success in business, Victory over enemies, and all round success.As per Hindu mythology, at the time of SAAGAR MANTHAN , the devil RAHU managed to drink the immortal fluid AMRIT along with holy angels DEVTAS Lord Vishnu became angry and cut his head using his SUDARSHAN CHAKRA But as RAHU managed to drink AMRIT , he could not die. As the result the head and the trunk of his body were still alive. Afterwards, these two parts of his body became the shadow planet by the name of RAHU and KETU KETU is an auspicious planet. KETU alike SATURN (SHANI) and RAHU , is said to be the SORROW of the KAAL PURUSHA . KETU indicates the position of the maternal grandfather of the native. It indicates the black magic, horned animals, death due to the animals with horns, dogs, hen etc. If KETU is in the malefic position in the horoscope, the native may suffer from enmities. KETU indicates the self-realization, understanding one own self, Vedic studies, knowledge, liberation from birth-death cycle, yoga, science etc.