Jupiter is a jeeva karaka planet and the guru in astrology. This single planet is considered to be the guru. It is said jupiter in ascendant is capable of mitigating thousand dosha in a horoscope.
Here I will discuss some golden words from bphs and how Jupiter as ascendant plays an important role to remove doshas in astrology. Jupiter serves as an antidote for all the challenges or bad doshas or less longevity in a horoscope. As per bphs
If benefic like jupiter, venus, mercury occupy lagna or occupy kendra that is first, fourth, seventh and tenth house.
A strong jeevakaraka jupiter in lagna can fight against any dosha of the horoscope.
A single strong jupiter in lagna in horoscope is like destroying all the evils of the horoscope.
If the ascendant lord of the horoscope is strongly placed in kendra it can destroy the negativity of a horoscope.
If the birth takes place in shukla paksha at night and aspected by benefic and in krishnapaksha during daytime, aspected by benefic in kendra can mitigate the negative combination of a horoscope.
As per bphs there are certain drawback or longivity issues when a person is born during amavysya, Sankranti, sandhya Kala, eclipse, birth during krishna paksha and chaturdashi. Especially when a person is born with moon in 6th, 8th, 12th house jupiter as ascendant can remove many of the doshas. It never means that there will be no impact of the positions of moon. Impact will be there but the native will be able to recover those losses.