Onions are associated with the underworld because they grow beneath the ground’s surface and have a sharp aroma. They’re used in magic to absorb negative energy and protect people from harm.
Cut an onion in quarters, leaving the skin on, and place the quarters in a shallow dish of salt. The dish could be placed under the bed of someone who is physically or emotionally sick, or anywhere you feel negative energy. This practice is best performed under a waning moon, but any lunar phase will work. Say:
With onion bulb and waning moon,
The negative energy will be drawn into the onion. When it has done its work, usually a day later, throw the onion away outside or take the trash out of your home. Clap your hands seven times to represent that the work is done. Finally, wash your hands with aromatic soap and take a deep breath, knowing the negativity is gone.