Mirrors carried openly in your inventory act as a weak source of reflection: if you have no other source of reflection, they will block an incoming ray (possibly only a death ray), at the expense of breaking and costing you 2 points of luck as breaking a mirror usually does, except if your luck is already negative it won’t be penalized further. Arguably it shouldn’t apply a luck penalty at all unless the player caused the ray; after all, you aren’t punished for a monster zapping a wand of striking and breaking a mirror on the ground.

This would allow better protection against random attack wands early in the game, when mirrors can be found but a permanent reflection source is rare.

Shields of reflection can be applied in a direction which is equivalent to using a mirror in that direction.

There should be some special effect, even just an acknowledging message, when trying to apply a mirror to a cockatrice, since the encyclopedia mentions its own reflection is fatal to it and the materials to make it look at its reflection exist in the game.

Wielding a mirror conveys partial reflection: you will reflect things 40 or 50% of the time.

New artifact The Mirror of Venus, a mirror that confers slotless reflection. If you are female, you can invoke it to charm monsters; otherwise, invoking it will only pacify monsters. Will only be gifted to a female character.

(Male counterpart artifact is the Spear of Mars, #2756).

Applying a looking glass cures blindness, in some very odd uncommon set of circumstances (like when hallucinating).

When applying a mirror at yourself, give different messages depending on your race, gender, and charisma.

If you apply a mirror at an empty square and that square is a “corner” (in a corridor), you gain temporary vision in the perpendicular line around that corner. If it’s a T-junction you look both ways. There is a “Done.” at the end like detect monsters has.

Monsters apply mirrors at you if you are a nymph or umber hulk.