Astrologers says that 6th, 8th, and 12th houses are malefic houses in any chart and their Lords will give malefic results only during their Mahadasha and Antardasha. People become afraid of this and think that their life will be gone in that period.

According to this statement, for a Cancer Ascendant native, Jupiter is 6th lord, Saturn is 8th lord, and Mercury is the 12th lord. If a Cancer ascendant native gets his Jupiter Mahadasha at the age of 10, then the next 16+19+17 years of his life will be full of struggles and failures.

But this is not completely true. When a hidden house lord become powerful and its mahadasha is coming then the period will give malefic results. If two hidden house lords conjunct or exchange their houses by Parivartana Yoga and become powerful, then that will also be dangerous.

But when hidden house lords become weak or when they are getting aspects of Jupiter or Venus, then their malefic nature will become reduced and may give benefic results.

Similarly, as the 11th house is the house of benefits, profits and success, planets sitting in 11th house will give only benefic results. This is also applicable for hidden house lords.

There is a story in our epic Vyasa Mahabharatha.

Before the birth of Meghanad, Lanka King Ravana wanted to make his son Meghanad invincible in all battles. So he arrested all the planets and put them all in 11th house from Lagna during Meghanad Birth Time. But Saturn wanted to defeat Ravana's bad intentions and put his one leg in 12th house from Lagna.

As all the planets were in 11th house, Meghanad was an invincible warrior and was defeated by no one except Sri Lakshman. But as Saturn put his leg in 12th house which is the house of defeats, failures, losses, and also death, Meghanad become defeated and died.

Only because of the beneficial nature of 11th house, King Ravana arrested all the planets and put them in 11th house. If else, he would have spared 6th, 8th, 12th lords. Ravana was very intelligent, and an expert in Vedic Astrology. Thoughts and Karmas by Ravana are highly trustable regarding Vedic Astrology.

So, we no need to be afraid of hidden house lords without analysing its placement, planetary aspects and his relationship with Lagnesh.