Planet Ketu, which is also a shadow planet, is the one which affects the Mo adversely. When it sits with Mo it gives the native some or the other sort of headache and the headache can be as serious as Sinus. The good part is that the native has strong intuitions. The intuitions can be good or bad depending upon the strength of Mo, planets aspecting it and its position. Just like Rahu, Ketu gives fruits of the planet in whose house it sits.
Ketu is said to be a giver of fame and success of the highest order, but when a person is at that level because of Ketu, the person will actually be alone.
A person when under the affect of Ketu, will have to live alone, away from home. Ketu forms an interesting yoga with Saturn in 12th house. The yoga is called Karawas (prison) yoga. It actually does not necessarily signify that the person will be incarcerated, but that the person will be away from his comfort zone, segregated from the rest of the world, may be working for a secret project.
Ketu is also signifies Moksha or final emancipation from the cycle of life and death. If Ketu is situated in 12th house alone and if it is exalted or with master of 5th house, the person is bound to get Moksha after the current life. Ketu can make a person highly spiritual if it has guidance of Ju.