I was once taught a working by The Morrígan in the Dreaming. As far as I am aware, there is nothing in the lore to support Her connection to this and thus it should be considered as UPG. I had debated whether to share for a while now, as I felt a call to do so, but wanted to wait a while to see if that feeling persisted. It has. I have since heard of similar forms of magic, so can not claim that this is something new.
To begin, I will share the dream.
There was a man who was infected with a malicious spirit. This could be interpreted either as illness or as a harmful energy or spiritual possession. I was led by The Morrígan to lay my hands on the man and breathe in the infection. As I breathed it in, so it was drawn out of the host.
The next steps were crucial. After the spirit or illness was removed, I had to go outside and release it by breathing it out of myself. I made a mistake and so it was free to find a new host.
After some meditation on the dream, I realized that I was supposed to have released it into the earth. The earth would then act as a filter. At the same time, there was a sense that this must be done carefully, as not to cause harm to the land in some way.
I feel that ritual or meditative components can be added to this work to ensure greater success. I am personally drawn to the use of water or fire (in visualization or as a tool) to act as a cleansing agent when releasing the unwanted energies.
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Disclaimer: The above information is not meant to be medical advice. Any medical issues should be treated by a licensed physician if possible.