# Protection from shape changers
Protection from shape changers is a property in NetHack that prevents shape changer monsters from transforming while you possess the property.
The only source of protection from shape changers is wearing or eating a ring of protection from shape changers.

Contents

1 Description
2 Strategy
3 Messages
4 Variants

4.1 SLASH'EM
4.2 FIQHack

5 References

Description
Protection from shape changers causes most shape changers and other similar monsters to lose their shifting ability:

Chameleons, doppelgangers, sandestins and vampires will appear in their base form; they are vulnerable to being polymorphed completely into another monster, and may suffer system shock as with polymorphing other monsters.
Werecreatures will similarly appear in their human form a majority of the time, and are still capable of shifting to animal form, but will shift back to human form on their next turn[1][2] - they also cannot summon help or infect you with lycanthropy.[3][4][5]
Mimics are de-cloaked and cannot disguise themselves.
Monsters with a digestion attack will not polymorph when swallowing a shape changer whole.
Strategy
Main article: Ring of protection from shape changers
While not strictly necessary to succeed throughout the game, protection from shape changers is useful to protect against early shapeshifters with abilities (e.g. werecreatures summoning help, chameleons and doppelgangers turning into very strong monsters) that can spell a quick end to your game. Players interested in keeping exotic pets such as vampires or monsters with digestion attacks may also seek out this property to keep those pets in their base forms (though this will not stop them from polymorphing by eating shapeshifter corpses).

Messages
You are protected from shape changers.
You have protection from shape changers as viewed via enlightenment.
Variants
Some variants introduce more sources of the property.

SLASH'EM
In SLASH'EM, The Medallion of Shifters from NetHack Plus and SLASH 6 is present as a defunct object. It granted protection from shape changers while worn, and could also be invoked to immediately return shape changes to their base forms.

FIQHack
In FIQHack, protection from shape changers is one of the properties that can be conferred by quaffing or dipping into a potion of wonder.

References

↑ src/mhitu.c in NetHack 3.6.7, line 600: chance of changing to animal form when attacking

↑ src/were.c in NetHack 3.6.7, line 38: changing back to human form always occurs if protection from shape changers is active

↑ src/were.c in NetHack 3.6.7, line 137: summoning help checks for protection from shape changers

↑ src/mhitu.c in NetHack 3.6.7, line 600: chance of changing to animal form when attacking

↑ src/mhitu.c in NetHack 3.6.7, line 1310: lycanthropy cannot occur with with protection from shape changers active