Ring of polymorph
A ring of polymorph is a ring that appears in NetHack. When worn, it causes you to polymorph at random intervals.
Generation
90% of rings of polymorph randomly generated in the dungeon are cursed, with the remaining 10% being uncursed.
Wizards may have a ring of polymorph as one of the random rings in their start inventory, though they will never start with a means of polymorphing and a ring of polymorph control simultaneously.[1]
Description
Wearing a ring of polymorph gives you polymorphitis, which has a 1% chance of polymorphing you each turn - this polymorph can also fail and induce system shock unless you have polymorph control, or else are wearing dragon scales or dragon scale mail.
If you have polymorph control, you may choose the form into which you polymorph. If you are afflicted with lycanthropy, the ring of polymorph will occasionally trigger a change into your normal form or the animal form of the werecreature that infected you. If you are wearing an amulet of unchanging, the ring of polymorph will have no effect beyond ring hunger.
Dropping the ring into a sink will polymorph the sink into an altar (of random alignment), a fountain, a grave, or a throne, with an equal probability of each (25%).[2]
Strategy
The ring of polymorph is one of several reasons that wearing unidentified rings randomly is a Bad Idea: even when uncursed, wearing one for any extended period of time may result in you shifting into a form that removes or breaks armor, has low carrying capacity or (worse yet) leaves you with no hands to remove the ring.
Identification
Informally identifying the ring of polymorph can be fairly difficult compared to other 300 zm rings such as the ring of conflict, as wear-testing after they are price-identified is very risky - an especially unlucky player testing to rule out conflict may find themselves quickly polymorphed with their valuable armor broken. While it is more likely to be cursed than other rings priced at 300 zm, it is by no means guaranteed.
In addition to testing for conflict by wearing the ring near relatively weak and/or peaceful monsters, you can also test for the ring of teleport control using a teleportation trap.
The odds of a ring that is price-identified and tested for beatitude is given in the following table:
| Testing done | Any BUC | Non-cursed | Uncursed | Cursed | Blessed |
|---|---|---|---|---|---|
| Any price | 3.45% | 0.50% | 0.52% | 10.14% | 0% |
| 300 zm | 25.0% | 3.6% | 3.6% | 75.0% | -- |
| 300 zm, not telecontrol nor conflict | 50.0% | 10.0% | 10.0% | 90.0% | -- |
History
The ring of polymorph control first appears in NetHack 2.2a along with the ring of polymorph control. The effect of dropping the ring down a sink is added in NetHack 3.6.0, and was integrated from UnNetHack.
