Conjuration

Conjuration was a form of magic that involved creating matter from thin air.

Description
Conjuration could range from basic substances like fire, light and electricity to more complex material forms such as inanimate objects and even living creatures. Since Willow Rosenberg and Anya Jenkins claimed that magic itself did not break the laws of physics, then it's likely that magic practioners did not truely make something from nothing, but instead brought matter forth into their dimension using magical energies from other dimensions. Magic practitioners had a tendency to use the word "conjuring" when summoning deities or beings during magic rituals, meaning that they were summoning that being from its dimension, making it real in theirs.

Examples

 * Willow Rosenberg started practising conjuration during her third year as a witch, having learnt the basics of magic before trying her hand at the next level which involved conjuration alongside transmutation. While not ready, Willow went out of her way to conjure a firefly, though this ended up backfiring when the firefly multiplied and attacked her. A year later, when in battle with Glory, Willow was able to conjure a snake, only for the snake to be easily broken down into nothing after Glory shrugged it off. By this time, Willow was already able to conjure powerful forcefields. The following months, Willow easily conjured party decorations for the announcement of of Xander Harris' engagement to Anya, along with plastic cups for drinks. According to Willow, the materials she made were "biodegradable" as they would go "poof" in a couple of hours.
 * Anya Jenkins, having lost her memory, aimlessly cast a spell, causing a rabbit to pop into existence. Fearful of rabbits, Anya attempted to vanish the rabbit by casting multiple spells, only to create dozens of more rabbits. Managing to get rid of them, she ended up making a living skeleton warrior and then unseen beast before being able to deal with those too.