Reflection

Reflection is an intrinsic, though it is only obtainable as such by polymorphing into a silver dragon and is therefore normally obtained extrinsically. It causes magical rays, such as ray of cold, death ray and disintegration ray to bounce back. It also protects you from Medusa's stoning attack and floating eye paralysis attacks.

Reflection can be aquired by wearing an amulet of reflection, or shield of reflection. Silver dragon scale mail and silver dragon scales also confer you reflection - obviously polymorphing into a silver dragon also helps. The final way of gaining reflection is wielding the Longbow of Diana, ranger quest artifact.

Reflection is a high priority trait. Usually the first time you may get it is by wishing for a silver dragon scale mail when you get a magic lamp from the Gnomish mines. Silver dragon scale mail is especially good if your character can do two-weapon combat because then you will have both hands for your weapons, compared to wearing shield of reflection. Some weapons, such as Cleaver, are also used with two hands, preventing the use of a shield at the same time. Also, most spells require that you have both hands free to cast them with. One-handed weapons don't interfere, but shields and two-handed weapons make it tough to cast spells.