Toads were integral in some forms of experimental divination. Toad excrement was said to be used as an ingredient in flying potions by Basque witches.

A lotion of sow-thistle sap and toads spittle was believed to make a witch invisible, and brandy embued with burned toad ashes was believed to be an effective cure for drunkenness.

If a toad was baptized with an enemy's name then tortured to death, the victim supposedly suffered the same fate.

In 1610 Juan de Echalear, a sorcerer of Navarre, confessed at his trial before the Alcantarine inquisitor Don Alonso Becerra Holguin that he and his coven collected toads for the Sabbat, and when they presented these animals to the Devil he blessed them with his left hand, after which they were killed and cooked in a stewpot with human bones and pieces of corpses rifled from new-made graves.

From this filthy hotch-potch were brewed poisons and unguents that the Devil distributed to all present with directions how to use them. By sprinkling corn with the liquid it was supposed they could blight a standing field, and also destroy flowers and fruit. A few drops let fall upon a person's garments was believed to insure death, and a smear upon the shed or sty effectually diseased cattle

Toads secrete a thick, white, hallucinogenic substance from skin glands when they are injured, scared or provoked. This toxin (C24H34O5) is called bufagin, bufotenin, or more colloquially, toads' milk.

The secretion acts like digitalis in biological action, and was believed to have been used by witches for various nefarious purposes. It is also a pagan custom in the South of France to “lick the toad”, young paysants were used to get high in the first days of spring by drinking this underground milk.