I will be presenting these as ideas, with as few rules as possible. They could be seeds for alternate classes, or just fun ways of reskinning the existing wizard class to look and feel a little different. They could be given unique spell lists, or be typical mages with full access to whatever spells are allowed in your system. Use them as you will.
I expect there will be several of these...
From the Greek καθρέπτης (kathrépti̱s -- mirror).
Kathreptomancers, or Mirror Mages, believe that magic is made of light. By reflecting, bending, breaking, and otherwise manipulating light they can tease forth a variety of extraordinary effects.
Method of Casting:
A Kathreptomancer's spells are always complex descriptions carefully written out with the off-hand while viewing it in a mirror. While true masters may be able to read it directly, most aspirants can only read this "mirror writing" by viewing the words' reflections.
The Limit: (i.e. Why does this guy have Vancian spell-slots?)
Light contains much more energy than the uninitiated are aware of and the Kathreptomancers tap into a great portion of that energy with their spells. There is only so much exposure to such radiations that a body can withstand before the strain becomes too much, though a body can learn to grow accustomed to it with experience and prolonged exposure. Once a Kathreptomancer has reached his daily limit of spells, he must rest, or risk doing considerable harm to himself.
Breaking the Limit: (Because allowing that last desperate spell attempt is awesome.)
A Kathreptomancer who has exhausted his daily allotment of spell slots can attempt to cast additional spells, by pushing past his body's ability to resist the powerful energies of the Light. A Kathreptomancer who attempts to cast more spells suffers 1 point of radiant damage per level of the spell being cast, and must succeed on a save vs spell or be Blinded. The damage dealt by this exposure can be healed normally. A Kathreptomancer that is blinded by exposure will have his sight restored after 8 hours of rest. A blind Kathreptomancer cannot cast any spells (as he cannot see the light to be manipulated).
When Kathreptomancers make magic items these most often take the form of "wands". No simple sticks, these items are complex contraptions of polished metal, glass, and crystals, charged with arcane energy and designed to produce a single, specific effect (typically a damaging ray of some kind). The devices almost always include a handle and a clear "business end" from which the Kathreptomantic magic is emitted and which should be pointed at the intended target of the spell.
Frickin laser beams!
Masters of Reflections:
At 20th level (or name level), a Kathreptomancer's understanding of his craft is such that he no longer needs the complex tools used by his lessers. He can cast any Kathreptomancy spell using a single handheld mirror or prism (a well polished shield or chunk of broken glass will often suffice) and any available light source. Likewise, he can understand mirror-written scrolls and spellbooks at a glance, without the need for a reflective surface.