The Alkahest is a weapon used to push the ability to control chaos out of a Makar, causing the void to destroy the Makar in the process. It is a gauntlet made of copper that was forged from a combination of all the elemental forces. It could be wielded by any mage, but it required the living heart of a chaos creature to give it power.
According to the book Alkahests and Other Indices of Magick, the alkahest is a universal solvent—a substance that can dissolve all things, from gold to diamonds to chaos magic.
Alastair Hunt used the gauntlet to destroy Constantine Madden's physical body.