M is for Mirror

You can use mirrors in all kinds of ways. You can reach into one and pull out a reflection of whatever is shown. If you're holding a gun you can pull out another. You may not be able to read the backwards lettering, but it works just fine. It's harder to pull out complex reflections like a person's, and they can't talk right, but otherwise they are identical. Just remember: everything and everyone only has one reflection, and it's not good to go without one for long.
You can even use the backwards reflection to reverse a situation. If someone is holding a gun to your head, you just concentrate and suddenly you're holding the gun to his head. If you are standing with a king, you can suddenly be sitting in his throne and order the guards to throw him out.

1-2: make a simple reflection pop out of a mirror. Copy weapons with simple mechanics and apparel. Reverse simple situational elements.
3-4: make more complex reflections such as one persons reflection or a computer. Reverse more complex situations. If someone is in a position of power and someone else is at their mercy, they can be switched.
5-6: call forth any number of complex reflections at once. Copy an entire party of people and all their tools and weapons. Switch a complex situation around. Make kings into peasants and powerful nightmares into frightened children. Just be careful of who you switch.

How do I change?
You begin using your power more and more. You can't stand being in anything less than the very best position in any given situation. You're constantly switching yourself around at a whim, even your form. You switch yourself with the most handsome person you can see, or the strongest. You constantly envy what others have and reverse things so that you have it rather than them.

What am I becoming?
Eventually you use too much of your power. You conjure a reflection and the mirror goes black as the reflection runs like liquid out of it, engulfing you completely. It feels like cool metal as it enters your mouth and lungs. All of your body reflects the world around it, and it takes on a mind of its own. It wants to take on every form, to no longer just reflect reality, but to become it. So it wanders from place to place, copying people and objects before destroying the originals. You've become the Mimic Mirror.