Cloak of magic resistance

A cloak of magic resistance (CoMR) is one of the few ways to obtain an important intrinsic. Wear this, and you can stop worrying about magic and teleport traps and become immune to any wand of striking or magic missiles fired by an enemy.

We know that such a cloak appears in the starting inventory when one plays as a Wizard. However, no other character has identified this cloak at the start of the game. Yet it would be useful to know which cloak gives magic resistance.

Consider this: the only other sources of magic resistance are gray dragon scales, gray dragon scale mail, and certain artifacts, and all of those do not require identification. (To check if your artifact gives magic resistance, ask NetHack: press [/] and type the artifact's name, for example "Magicbane" or "Eye of the Aethiopica".) So, if you find yourself with magic resistance but none of those items, blame your cloak.

A strategy is to wear one of the rarer cloaks (not the common, cheap kind most often dropped by monsters), then wait until you accidentally step onto a magic, teleport, or level teleport trap. If you successfully resist the trap, then the cloak is magic resistance. Go #name it MR.