Vish Yoga is formed when Saturn and Moon are together or when Saturn aspects Moon. It is not a good yoga and person born under this yoga can do harm of persons represented by the house in which Saturn is placed. Shani and Chandra Yuti, generally considered as VISH YOGA (poison Combination) and it does creates bad effect on mother and her health particularly. But more importantly see the 4th House of the Native for Mother Son / Mother and Daughter relations.
Saturn poisons the natural emotions of Moon causing lack of expression and emotions from native. These people are hard working in nature but success comes after the age of 30-32. They generally land in to service industry after series of failures. They are strict in discipline and make a good administrator.
This Yuti gives Bad effects during each Others dasa and antar dasas. It reflects losses of the House where both the planets are located.
eg. If this Yuti is in 5th House then, Chandra Mahadasa with Shani Antardasa or vice versa will give bad effect to native, which leads to failure in exams, sudden change in education streams, failure in love affair or problems to son/daughter of native.