One of the more interesting NetHack wands to play with. Zapping a wand of polymorph at a monster, an item, or yourself will change it into a different monster, item, or self. In that last case, your stats are re-rolled, certain bad things go away (lycanthropy, stoning, food poisoning), but you lose other intrinsics. Furthermore, most of the time you'll wind up changing into a random monster, unless you have polymorph control. Note that polymorphing causes you to undergo a system shock roll; if this is failed, you will suffer around 30 points of damage.

Polymorphing other monsters is a possible means of escape from death, but you'd better have more than one charge on the wand (and pumped-up speed, just in case). Changing a giant ant into a mind flayer only makes matters worse, generally speaking.

Polymorphing an item will usually change it into an item of the same class (your wand of light will not become a scroll of genocide, but it might become a wand of fire). "Polymorphing an item" is now listed as a voluntary challenge because of the way this item can be abused. "Polypiling" is largely regarded as unscrupulous by the NetHack community -- this is when you put a bunch of items on the same square and polymorph all of them at once with a single charge from a wand of polymorph. Deplorable. It used to be much more effective when a polymorphed item could change into anything.