Parivartan Yoga is formed when two planets interchange signs with each other.
When Jupiter is in one of the Kendra houses(1st, 4th, 7th & 10th) in its own(Pisces), exalted(Cancer) or mooltrikone(Saggitarius) signs them Hamsa Yoga is said to be formed.
This vedic astrology article shows how afflictions comes to planets and houses.
Maha Bhagya Yoga and its effects are mentioned in this article.
maraka planets can create health issues in their periods and can also kill if it is severely afflicted and ascendant lord is weak.
Sasa yoga is one of the panch mahapurush yoga by planet Saturn and bless