The Eighth House Mystery In Vedic Astrology: Transformation, Obstacles & Longevity

General Characteristics of the 8th House
The Eighth House is known as the house of “Transformation, Obstacles & Longevity”. It is one of the moksha houses, a house of enlightenment, indicating what must be changed, left behind or transmuted for purification of the identity and spiritual liberation. It is a house of great mystery, the hidden depths of the persona, carrying the highest and lowest of human expression and experience. A strong 8th house indicates a healthy mental and physical constitution, ease in overcoming challenges that naturally occur in life, and longevity. The hidden depths of the 8th house also bring the karmic undertow of criminal intent and criminal behavior. It is a house of both sexual deviancy and kundalini rising as well as the continuum between these two points. Whereas the 7th house is the sexual relationship between two people, the 8th house is sexuality and the sexual act. If this house is disturbed, it can bring sexual deviancy. If it is strong and healthy, and the individual is on a high spiritual path, it can bring the capacity for tantra, a science developed by the Siddhas to transform sexual energy into spiritual energy; thus the transformative potentiality latent in the 8th house becomes realized.
The range of kundalini describes the range of potentialities held through the 8th house. Kundalini just awakened but difficult to control is expressed as the Goddess Kali. This is associated with the subconscious mind (things hidden). When this energy has become controlled and brings peace, it is the Goddess Durga (death and destruction). When fully awakened and manifesting as positive creative (transformative) power, it becomes Mahalakshmi, Saraswati, and other forms of Mother Divine. The 8th bhava can also bring psychic abilities. As with any gifts, and especially these, proper unfoldment is crucial for unlocking their highest benefits. This includes having correct intention in using them. Else, misery and psychological disturbance prevail.
It is the house of the dream world and can bestow the ability to remember and interpret dreams. As the “house of death”, in indicates longevity and also the capacity to experience samadhi, both expressions of the ‘dying’ of individual consciousness, and dissolving back into universal consciousness. Thus, St. Paul’s famous description: “I die daily.”
Materially, it is the house of all things hidden. This includes hidden mental and psychological disturbances, hidden wealth and serious diseases. It also concerns ‘unearned wealth’ such as well as lotteries, inheritances, and gains and losses from the stock market. As a secretive house, it involves research & development, investigative and intelligence activities. Hidden agendas and motives underpin criminal behavior, or unethical dealings. Certain planets placed in the 8th bhava can bring a tendency to be underhanded and dishonest.
As a house of legacy, it is also a house of scandal (negative legacy). It is the house of transforming consciousness. As such, it holds the potentiality for drug addiction as well as nirvana (bliss consciousness). The seeking for experience beyond ego boundaries is defined by the 8th house. It is conceivable that an individual who has overcome addiction can then transmute 8th house karma to experience samadhi which is the 8th limb of yoga.
Your personal 8th house – its ruling planet and chart position, planets influencing the 8th house and its Lord (ruling planet) will also give clues as to your own Achilles heel. These will also indicate benefits given by the 8th house, such as a long, healthy life. Keep in mind that as we evolve, so, too, do our planetary qualities and influences.

In Vedic astrology, 8th House signifies Longevity, Mangalya (marital bond) in females among other things and placement/aspect of Mars on this house can lead to problems related to these significations in certain cases.

 Article Reff: from astro websites.