Mirage Masters is a term from Tokyo Mirage Sessions ♯FE.
People with extraordinary Performa. They can also see each others Performa awakening, as well as when it is being sucked out of somebody, but common people can’t. As the title implies, a Mirage Master is able to form a sort of bond with Mirages that allows them to borrow a Mirage's power. When a Mirage grants a Mirage Master this power, the Master's appearance changes to reflect this bond and affects traits such as their wardrobe, hair color and style, and skin markings. This is what it's called their Carnage Form.