Arguably the most common type of magical mirror is that which traps those who behold their own image within it. There is of course the Mirror Of Life Trapping, referred to in the 1st edition of the Dungeon Master's Guide, but that's a bit more elaborate than the classic, simple, immobilizing mirror which I'm envisioning. Also within that sage tome, you'll find the Mirror of Mental Prowess and the Mirror of Opposition. So mirrors being all the rage this week (see bat's Mindseye Mirror and Lord Kilgore's Mirror of Yesterday spells), and not finding written elsewhere what I've been looking for, I thought I'd document my own modest creation here...
Mirror of Transfixion
Also known as "Mirrors of Invanity", anyone who sees their own reflection in them must make a saving throw against Paralysation. Charisma Reaction Adjustment scores are tripled and then added to (or subtracted from) the roll. For example, a 2nd level fighter with Charisma 18 should subtract 6 from their d20 roll, effectively requiring him to roll a "20" to save. Similarly but conversely, a homely 1st level dwarf with Charisma 8 adds 3 to his saving throw roll, effectively requiring only a "7" to save.
Failure to save will cause the victim to stare at their reflection in the mirror in total self-love and admiration for a full day. Attempting to break their gaze or to take the mirror from them will result in a furious attack until they are unconscious or until the mirror is returned, whereupon gazing will begin again. Breaking a mirror which has currently bewitched anyone will cause damage equal to one third the Charisma score of the victims, rounded down, +2HP per character level. Victims can be moved by being pushed and pulled about, as long as they're permitted to continue primping themselves and staring into the mirror.
Mirrors of Transfixion can come in any size, although the smallest are most desired as sources of entrapment and mischief. These pocket sized items are usually made of silver, their delicate and ornately decorated outsides being hinged, hiding and protecting the mirror surface itself until opened.
Update: I struggled a bit with determining how to calculate damage if a bewitching mirror is broken, although I'm sure I want it to be at least partially dependent on the charisma of the character - suggestions welcomed!
Image source: CC licensed photo by flikr user caryatidxx, GIMP'd by le bulette and also CC Attribution-Share Alike 2.0 Generic licensed :-)