The only source of the property is wearing the amulet of unchanging.
Unchanging stops polymorphing and other means of changing form from occurring, including sliming and the effects of eating certain corpses or tins, but not stoning. If you gain unchanging while suffering from sliming, it is aborted and cured.
If you die while polymorphed (which would normally return you to your normal form) and have unchanging, you will instead die as normal in most cases. The exception are as follows:
- While in the form of a wood or leather golem, be hit by a brown pudding bite and rotted away.
- While in the form of an iron golem, be hit by a source of water or a rust monster attack.
- While in the form of a clay golem, be hit by the intrinsic-stealing attack of a gremlin.
- While in the form of an undead monster, pray to your god.
In the above circumstances, you will be returned to normal form even with unchanging.
Unchanging is typically used to maintain a long-term (and often controlled) polyself for various purposes, in exchange for the risk of deaths that occur being permanent where they would not be otherwise. A source of unchanging can also be a good substitute for magic resistance in areas such as the Gnomish Mines beyond Minetown, where polymorph traps are a major obstacle; unchanging can also protect your steed from polymorph traps while riding. Unchanging can also suppress unwanted polymorphing from other sources, such as lycanthropy.
- You can not change from your current form.
- You have unchanging as viewed via enlightenment.
Some variants implement additional sources of unchanging outside of the amulet of unchanging.