We already know that the Eihwaz rune can be used to stimulate kundalini when ready, intensely fortify the will and sublimate Pluto, but I have some questions.
Since it is a power rune on the dead can it be used to defend against the influence of ghosts that are weaker for example with an aura of protection made for departed beings who are in the astral?
Can it be used before an automatic writing session and other mediumship work to strengthen the operator's will and thinking?

I think it is a particularly useful rune for those with a strong and present Pluto / Scorpio in the chart including the presence of an important eighth house and in natural mediums because it can act as a fortifying screen that enhances will and strength of spirit this could be worth the contrary in the sense of astrology applied to necromancy?

How can it be used for example to empower the souls of departed Satanists while they are waiting to be reincarnated?

Can it be used, for example, to prevent loved ones who have passed away from dissipating in the astral?

For example, can it be used before the reincarnation of a deceased person in order to preserve the wisdom and memory of life as much as possible during the reincarnation process?

Vibrating this rune while fused with the soul of the past one you are working with can be helpful while ascending the kundalini serpent energy.Working with the kundalini energy of a very advanced departed Satanist in order to cause him to ascend kundalini and prevent the past life amnesia during the reincarnation process?

How can ectopasm be used in conjunction with this rune to allow for a denser manifestation of the spirit of the departed?

The rune Eihwaz can be used to harness enough psychic energy to better communicate with the deceased, on the astral.

The rune can be used to charge other spirits, so that they will have the necessary strength of a good passing, and the ability to reincarnate once again. This is advanced. You would need to be psychically open enough to see and communicate with them. The rune is to be worked upon the deceased's chakras.

Theoretically, yes, one could help an advanced soul to ascend. If a Satanist is very advanced, chances are that Satanist would still be reincarnated in a physical body to work upon their soul, where they ascend their Kundalini.

An ascended would eventually remember their past lives.

When you see the 'white clouds' when you are scrying into a mirror, focus upon that cloud and vibrate Eihwaz. After vibrating Eihwaz, you have to program the energy into what you desire. Considering you are using Eihwaz for this, you should keep in mind to always exercise with great respect when contacting the deceased.