Mutotheurgy, as the use of Mutomancy is called, is the art of magic based around different forces of change and transformation. It is the arcane manipulation of magic to achieve effects based around transmutation, radiation and chemicals. Through their magic, they are capable of altering things in a wide variety of ways, with spells acidic or atomic in nature.
One of the magical arts developed after the founding of the magical schools, Mutomancy is a form of magic that is rarely found outside of civilized areas. Many of the spells are based off of advanced concepts that more primitive and uncivilized areas don't have an understanding of. Due to this, it is not a common magic, though it is more common than the newer magics of the Fourth Age.
Capable of altering objects in a variety of ways, Mutomancers are able to find a wide variety of work. The tend to have good relationships with alchemists, who's work with various chemicals and substances is easily relatable. There is some ill will towards Mutomancers, as their magic tends to linger longer than others and have more drastic lasting effects. This isn't due to their magic being more powerful, but simply due to the substances they control.
In the Second Age, the concepts of Mutomancy started to form, but it wasn't until the Third Age that Mutomancy became a fully fledged magical art. It was an extremely attractive magical school when it was new, but it has faded somewhat in interest. They have recently been finding more and more use by the armies of the Planar Militia, as the Recreancy hasn't developed the art to the extent that the Planar Council has, making it an effective tool against them.