Basic magecraft that replaces something with something. It derives from a primitive alchemy that aimed to transform metals into gold.
Giving the target an arbitrary directivity and changing it physical or conceptually by something close in an instant is the ordinary displacement magecraft. In short, it’s a mana shortcut for chemical and conceptual changes of the target. But in the process of displacement, a degradation in the target will definitely occur. For example if a spoon is continuously replaced by a fork, and a fork by a spoon, its shape will become more and more like an ambiguous spork, and in the end it will become a warped metallic spatula.
The scope, accuracy, and application range of the displacement magecraft used by the Ainsworths deviate from the common sense of magecraft. It’s not hard to imagine that they are using some trickery.