What is it? Basically, it is water + nails.
Why nails? Nails contain a lot of iron. Iron has a strong anti-magic connotation. It is used to repel spirits/ fae as well.
What is it used for? Repelling magic, reversing magic, returning magic to the sender, absorbing negative magic, protection, warding against negativity, cursing, psychic warfare (when you’re fighting with other witches).
Additional ingredients: urine, Spanish moss, blood, black salt, salt.
Additional information: It might turn black. That’s normal. No worries.
Some witches prefer not to keep this in their house, and would rather keep it on the porch or patio, perhaps because it may nullify any spells/ workings.
If you add your urine, it may stink to high heaven. It may fill up your entire house with a wretched smell. I speak from experience. Maybe it’s something I ate.